I show testing ot see if the fuel pump check valve has failed causing a extended cranking time. Sorry about the dark video we have 2 lights in the shop with bad ballasts.
This doesn't determine whether it's only the fuel pump or a leaking injector. Just losing pressure on the fuel rail can be a multitude of things. Leaking injector, bad pump check valve, or pressure reg bad. On this car you checked the FPR but not any injectors. Just an FYI for anyone watching this. If you pressurize the system and pinch off the fuel line once the pump turns off, you will either lose pressure (meaning injector problem or FPR) or hold pressure (meaning pump check valve is bad). If you do the same and pinch of the supply and return and don't lose pressure, your injectors are good and your FPR is bleeding pressure to the tank. And if you lose pressure at this point, it is a leaking injector.
@ZSmith-tp5rm should be the same as I described. As long as you have lines that can be blocked or pinched. Concept is the same on any non direct injected system that uses a fuel pump. An injected that failed stuck open could do it, remember psi in liquid is barely anything compared to air.
Thank you for the video Kevin ... It is a good habit to replace the fuel filter as well once you replace the fuel pump (restricted fuel filter will create a back pressure which will shorten the life of the fuel pump).
It's the spped of the bleed off that's really the best indicator. In the span of 5 minutes you saw your pressure drop to nothing (assuming no video editing for brevity) A leaking fuel injector on the rail would show similar symptoms but take longer to bleed off the pressure as in an hour or more instead of a few minutes. Only way to know without a doubt, however, is to block off the return line on the rail (assuming a return system) to know for sure since then you'd be able to isolate the pump check valve from the rail to see what's leaking.
Wow amen finally someone who is on top of why an engine over cranks before starting.i was told everything under the sun about what the problem is,starter,battery,ignition,bad fuel pump relay,bad grounds,bad batt terminals,crank sensors,camshaft sensors,pcm,tipm,on and on,thanks again
Why not just replace the check valve or ball? It looked like the pump was working fine. You could even install a generic check valve in the fuel line just past where gas comes out of the pump, but before it gets to the fuel rail.
fun stuff, in my case when I finally got the truck started it would still only hold about 10 psi bellow spec so my regulator was bad for sure, replaced it and now get pressure within spec BUT the pressure bleeds off immediately when the engine is stopped. Same thing happens if I jumper the fuel pump diagnostic port to turn on the pump. So, looks like my check valve in the pump is also bad. fun stuff. at least I've learned how to do diagnostics on the my entire fuel system which is priceless information :D
$800 repair (I was stuck away and had to have repair). Instant start!!!! It was great. Now I have THIS bleed down problem. So far, my solution has been to turn the KEY ON, WAIT for the system to pressurize, and BINGO, it works. From everything I've read here, that is just an annoyance and nothing worse.
Yes I have observed the same thing that it is at most an annoyance. I had a similar situation with my truck but only with the rear gas tank so I would just start it using the front tank. Even with the rear tank it didn't bleed all the way off until a good 12 hours anyway so could easily restart during that time. No other problems no fault codes, etc.
Mister Moonshadow, so dis the problem eventually get worse till you finally had to replace what ever the problem part was? I've been doing the same thing on my 91 4runner v6. It was working for a while, putting the key to On, letting the fuel system pressurize. Or simply clicking it on ON several times but the system bleeds out faster then b4. I replaced my fuel pump 3 months ago with a cheap $30 Amazon fuel pump. I'll be replacing it now with an OEM Denso fuel pump.
Great video...helped me determine my fuel pump is bad on my 2003 Pontiac grand am....hard start after sitting for awhile...after it's running no issues...starts right back up...thanks alot
Can the fuel pump check valve be intermittent? My wife's 2000 Bonneville will not start sometimes unless the accelerator pedal is held to the floor. Usually happens after sitting for 24 hours or more but has happened after filling the tank with gas. Fuel pressure checks look good but I have not had a chance to check pressure when it is acting up.
My ranger is doing that and throwing lean codes. To start it right now, rather than crank and crank, I bump the key to give it an extra squirt. I'm definitely going to be checking that. Thanks.
Could this cause a lean condition? Fuel trims show the ECU adding 10.9 to 12.5 % more fuel in the long term. Tested with a fuel pressure tester an i start my truck with less than 5 psi. Once running its solid 32, kill the engine an instant lost of pressure. Spark plugs are bone dry so not injectors. I havent check the FPR since its really hard to get to but ill test it tomorrow at lunch
Good job and great video... I'm getting ready to change the fuel pump in my 95 ss impala x highway patrol car.. don't know if it would be easier to drop the tank 3/4s full or go three the trunk and cut a hole...
Great video..however not all cars have a external regulator. Therefore you'd be checking injectors.or replacement of the entire pump module thanks for sharing
Best guy man I have heard honda crv mk3 pump alright injector fine glow plug fine in the morn crank crank the it gos then it start allday until next morn do I need to order inline check good vidieo lad been doing car all my life nearly beat with this thing 2007
03 Suburban has a 2-3 seconds extra longer than normal crank time but it has only happened 2-3 times over the last 2-3 weeks. Seems like a check valve issue but not sure why it is infrequent at least thus far. Should the pressure hold overnight at some minimal value? Pump is OEM and I just changed it 3 years ago! Not looking forward to having to do that again if it is the pump. Thanks for the video
I can't start car at all, cold weather, got integrated gauge for fuel pressure. Very rapid dropping pressure, but while I was checking all, it seem not priming the pressure before as well, found one of relays not very good.
great video kevin,I would like to see more videos using the scanner, since I have one just like yours,so I can learn how to use it too along with the videos,thank you cheers from ontario california
I don't believe so, as the pump is operating while the engine is running. The check valve is only there for when the vehicle shuts off, it's hold pressure for a certain amount of time as to not dran the line completely
Thanks for sharing the video! I have the same problem with my 98 Tacoma. I was almost positive that was it but didn't know how to check it. Can you take the hose off of the fuel pressure regulator any time while it's running?
Would that also cause a no start I have a 2004 GMC Safari with the MiFi I please and have the same issues I pinched the return line off and run the gauge and it holds pressure I let off the return line and it drops back down but I have a no start with that
+Kevin Criswell I have an early 90's Ford V8 5.8L EFI engine. When the system was checked with a pressure gauge, the pressure dropped too quickly. I've been told the check valve is bad on my fuel pump, but I have reasons to doubt it. First, it starts fine every time when cold (first thing in the morning, etc). The hard starting problem shows up after the engine is hot. Second, this is a replacement fuel pump that is only 3 years old with very low mileage on it. Also, during hard starting (when the engine is hot), if I press the accelerator, it helps the engine start. Any pointers or tips you can give me about where to look next? Thanks.
onesimpleidea try checking the fuel pressure regulator. Start the engine and than unplug the vacuum line and see if there is fuel coming out, there should not be.
Also check the temperature sensor, if yours is reporting a false cold engine it will add too much fuel when hot because the ECM will falsely assume the engine is still cold and needs more fuel.
How can you test the check valve if the engine won't turn over? I have a 2005 Chrysler T&C, that it had an elongated crank time one day, then eventually started, just as you explained, & drove fine. The next day, it wouldn't start, just kept cranking, no start. A mechanic told me it was the fuel pump & not worth the cost to change it, due to the age of the vehicle & mileage. I just received in the mail an Extended Warranty on the Fuel check valve for the van, stating it would need to be replaced either at the dealership or they would reimburse for repairs already made. I asked the mechanic if it was possibly the valve & not the pump, & he said he doesn't think it's the valve, but didn't check it. Is there a way I can do that, to see whether or not it's worth having it towed to a dealership to get the valve replaced? I'm not all that car savvy, so I don't even know if they are related issues.
Is this also applicable to Audi Quattro A4 1.8L Turbo engine? Isn't the fuel pressure check valve for the Audi Q A 4 located under the hood and not inside of the fuel pump? I had the same symptoms and found a that the car had a broken crank case breather valve....
hello, i have the same problem, in the morning, my van struggling to start and the engine shaking badly. once it started up, it works fine, but lately it been running under power and the only way to make it full power again is to shut the engine and start it up again. but my van now is dead and not starting up. I check the fuel pressure by loosing the pipes to the injector but very low fuel pressure coming. is it the high pressure pump or the regulator? my van use bosch cp1h fuel pump. sorry for my bad english and please help me. im dying to know what the problem is.
Thank you for this. I am having an issue with my truck not similar to your issue but I still wonder if it's the check valve. Under warm start conditions my truck has a very rough acceleration. If it's started from cold it will run fine.
Great video explained very well . Will A bad check valve cause any popping sounds and will it stall while driving, i am having some stall issues with a strght 6 bmw motor that most main sensors have been changed as well as plugs, coils , it,s only got 120,000 kilom.... can you help Thanks
I have 1988 IROC-Z. Hard starts begin to happen about 2 weeks ago. I replaced •alternator •fuel pump •pressure regulator For example, it will start in the morning...idles rough@2500 rpms. Then levels off at 1300 rpms.... Once I turn it off, it will not restart. Maybe 3 hours later, it will fire up again. Could it be my fuel filter? Or just a bad fuel pump...?
Hi Kevin: My car will crank up on 1st turn but will have poor idling if I parked car for more than 15 hours. So what I do is every morning, I turn the key on position 2 for about a few seconds, then the car will start up normal otherwise it will have poor idle for about 20-30 seconds. Can I just keep the car like that without fixing the check valve since the car is old not worth throw in any more money. Let me know. Thanks.
I'm confused where the check valve is on the fuel pump and how it works with the return line. If I crimp the line after the fuel filter, the pressure holds. Crimp the return line after the fuel regulator and the pressure holds too but if it's a bad check valve I'd expect the pressure to drop even if the return line is crimped??
Thanks for that video Kevin. I too am having a hard first start to the day. So I did this test, but my gauge showed that the pump is holding pressure, or at least during the five minutes I was waiting for it to drop after shutting off the car. So I did a little more research and was told that my condition can also be cause by an injector leaking down into the cylinders, filling the associated cylinder with fuel and causing my rough start, but how can my fuel gauge show that its holding pressure?
kevin, you say extra/long cranks is bad for the entire system, but isn't the oil pump doing its job of circulating oil inside the engine even before it turns on?
Sean J. It's bad for the starter motor & the battery. Those are not internals of the engine that get lubricated with oil pumped through the internal parts of the engine. Even the internals get the worst wear & tear in the first start up of the day because the oils & coolant have bottomed out till they start getting lubricated from the regular operation of an engine. Collant also lubricates the water pump. Transmissions have gone bad from sitting on vehicles without running for several years. Most people won't believe it.
Wow! Great information. Just installed a fuel pump on my Saab 900 Turbo. I've had this problem for a few years (fuel pump pressure). Just recently got worst starting up. Now that a new fuel pump is in, car still will not start. Question: My fuel pump fuse shows no output when car is switched on and probe light doesn't light. Isn't it suppose to light with this step.
Man, you don't know much you just helped me with this. hard start in cold morning and fuel pressure goes immediately to 0 PSI after shutting engine off. so fuel pump check valve, right?
Probably the speed at which it dropped, but to be sure you could isolate the tank from the injectors by pinching the lines with rubberized vice grips. If the pressure still drops after pinching the lines then it's probably an injector, or it could be the fuel pressure regulator if yours is in the engine bay.
HELP: My truck (GMC Denali Yukon) stopped abruptly while driving, 3 times and every time restarted but I suspect something wrong. Possibly beginning malfunctioning fuel pump. I additionally had code P0140 (Bank 1 senor 2) error that did not reappeared after erasing and cleaning the wire connection of driver side post catalytic O2 sensor. To check for fuel pump check, I bought a set From Harbor Freight (Fuel injector check kit for $20). I connected the gauge directly to shredder of my truck. With out start and with only turning key to ON, pressure is initially 50G but suddenly drops to 0 as fuel leaks (Pours prominent) off the gauge connection end of the tester unit! This happens exactly from where you thumb is @ 3:45 of this clip, joining the gauge meter to tube. So understanding it is not safe, I did go to start but after covering with tower and holding, temporarily running engine showed an stable low pressure of 35 G. I suspect my fuel pump is bad but WHY leakage from gauge meter? Or is it a usual problem with Harbor Freight tools? I am going to return to HF and change the meter. Hope I get a better one but is there any experienced one out there that can tell me what is going on and why I have leak at meter end of pressure check gauge?!!
My car long cranks when warm. Ok when cold. Returnless system. Checked for hold pressure and it does not hold. When I try to warm/hot restart after 20 30 minutes fuel pumps quickly up to the fuel rail and then boils off quickly into a vapor and temporarily vaporlocks. The pressure continues to build quickly and condenses the vapor back to a liquid and then injects into the cylinder and then she starts. On a cold start there is no vapor lock and the engine starts very quickly even with zero pressure in the fuel rail before starting. The fluid moves up the fuel line and thru the injectors very quickly on a cold start. (Very strong pump)I think some residual fuel is sitting in a cylinder or 2 from the leaky injectors so that probably helps it start when cold also. I’m losing pressure at the pump and a smaller amount thru the injectors. I isolated both sides of the system and verified leak down of both sides. I’m going to put an inline check valve after the fuel pump and then pull my injectors and verify leakage at the injectors and probably replace them. If I could maintain a lot of pressure in the fuel rail on a warm/hot restart,I would not get the vapor lock as fuel does not boil off at higher pressures. If a lot of pressure bleeds down after sitting overnight that would eliminate vapor lock on the cold restart.
My fuel pump went out on my 2000 Montana ,changed it and it ran fine for awhile then it died. Now I have no start and a sound like there is air in the lines near the engine , also when the pump is engaged it also sounds similar checked the lines in the tank and see no leaks from the pump. The fuel pressure is good. Never had one pull this on me . Anyone have a idea what its up to ?nThanks
I think the biggest problem would be ensuring a seal that would last the vibration and heat under the hood. Amazon often has master fuel pressure testers inexpensively.
I have an intermittent long cranking at cold start or warm start on my 2005 silverado. I tested the fuel pressure, it held at about 53 psi for a few minutes then slowly dropped to about 20 psi in about 40 minutes. I was told after an hour the pressure should lose around 10 psi. Any suggestions? I did the same test on my friend's 2006 silverado, except his truck lost about 8 psi after an hour and held at about 45 psi
Having your same symptoms as you with my 02 Silverado except mine dropped 20psi in the first 20min did you ever figure out what it may be? I’ve changed the fuel regulator but I have no clue why i slowly lose fuel pressure the guy I bought the truck off of couple months ago said he changed out the fuel pump and fuel filter I just forgot to ask how long ago
98 sebring turn key many times to start three tries and it runs finewas told it could be check valve in fuel pump in tank. why not in stall a check valve in line in route to hold pressure to engine also how about adding a 12 volt fuel pump in line to push fuel to aid starting only?also if it will pull thru old pump?. so don't have to drop tank
Karen Roman, Your idea is the idea that I plan on doing to my classic 1979 El Camino since it's a carburetor (not fuel injected) engine & I only drive it once in a while. I would use a Y tube connection so that fuel from the gas thank goes in one direction and out through 2 exits, one directly to the 12 volt electric fuel pump, & the other exit to your regular fuel injected system. Use a togle switch or button switch to activate the 12 volt fuel pump for a few seconds till your car starts then shut off the toggle switch to let your regular fuel injection take over. The problem is that if u inject too much fuel in the engine, you will hydrolock it. Ba-bye engine. For my carburetor engine I would only flood the carbereator so I won't be able to start the engine till some of the gasoline evaporates. Since you posted your comment a year ago, what did u do? By the way I'm having a problem as described in this video for my 1991 4runner v6. I'm sure my problem is a cheap $30 fuel pump that I installed 3 months ago I bought from Amazon. I'll be replacing it with an OEM Denso fuel pump.
One off the problems is the pumps check valve is calibrated to bless down pressure over a set period of time. Most modern cars now don't rely on the check valve to prevent heat soak hard restarts. The pump is often brought online and primed once a driver's door is unlocked or opened, with some doing it as soon as the keyless fob is brought into range.
No, most carb vehicles use a mechanical pump driven directly by the camshaft. Those don't need to hold pressure as the float bowl should contain enough fuel to start the motor. Sometimes though mechanical pumps do contain one way valves to prevent fuel from being siphoned back into the tank. To test this kind i personally pinch the rubber line going from the tank to the carb (sometimes it's metal and you may have to disconnect it) and see if there is a difference the next day on start up. Also a bad fuel cap on older systems can fail and cause the fuel tank to drop into a vacuum pulling the fuel back to the tank on shut down. Most modern cars do not have this issue as the evap system is monitored and will alert the driver to a fuel tank pressure issue.
Hey can anyone help me I have a 1987 Honda prelude, not starting after few months of sitting and there is no fuel pressure going to the engine, I have replaced the fuel pump with a second hand one was alot better condition than mine was in any advice would be helpful thanks
@@kg4tnp I can't seem to find that relay and i believe the fuel pump is working like I can hear it winding but no fuel pressure to the fuel rail or fuel filter I think it might be a bad fuel pressure sensor?
chris b Yes when the fuel injectors are leaking make the same reaction in the gauge, the pressure drops when you shut down the engine, but the car have a rich mixture condition (not lean condition) and you have a hard cranking too.
On Toyota 4runners also. I'm having this exact problem on my 1991 v6 4runner 3.0. At first I thought it was occurring on cold mornings or nights nut I came to realise that it was occurring only on the first start of the day, then throughout the rest of the day it would start right up without no problem just as he mentions on this video. Nothing to do with cold weather specially here in southern California. Gas pressure was slowly decreasing overnight & all gone by next morning. Now it's worse. Fuel pressure is decreasing faster so it takes about 3 cranking tries after 3 hours of not running. I. Hanged the fuel regulator. Not the problem. I was about to change the fuel pressure dampner nut now this video convinced me it's the check valve. But I'm not sure if it's within the fuel pump or somewhere else. But since I bought a cheap fuel pump for $30 on Amazon 3 months ago, I've been suspecting the cheap pump is not giving the proper fuel pressure. Sorry bro, made this too long.
i just spent a day trying to clean my check valve on the fuel pump to my motorcycle carbs. ended up ordering the parts. not too easy to service these valves but I actually found a couple write ups on the procedure but they were for valves with nylon plugs, mine are brass so drilled them out and now are dead. I suppose I could try to make a piece of nylon cubed and stuff it in there. oy vey
If pressure drops that quick, it's the check valve. Should take a LOT longer to drop pressure, if only one injector stuck. Also, if only one stuck open, that cylinder would be flooded, but rest would fire normally, and still start "almost" like normal, unless a 4 cylinder, then start would be less like normal, but should still start, maybe pop and then run. Also, on many, especially older vehicles, you can easily install an inline check valve and "poof" problem solved, and fuel pump could work for years more. Exceptionally stupid (normal) engineers created this integrated check valve/pump problem.
@@znzmanager Nah, the engineers had little to do with this bad design. 100% they said "this is stupid, we should not do this" and some asshat in upper leadership said, "Yeah, but if we integrate it then the whole pump needs replaced when it fails, bigger profits!". And upper leadership always gets the sign-off on shit like this, so we end up with dumb shit that's designed to cost more once it fails, aka, planned obsolescence.
Hey Kevin! Im getting an instant drop in pressure when I turn the key off. I replaced the pump but still getting the same thing. Wheres the check valve on a 91 sunbird 3.1?
+Kevin Criswell I tested all injectors measuring resistance. Replaced the two that showed a bad reading. Cleaned the rest. That got the car to actually catch and run. Before that it would just crank..crank and crank. Ill take a look at the regulator. Thanks!
toolman talal I have a 2001 yukon denali. throwing no codes, it;s bleeding down with no outward leaks. regulators been changed and had no effect on the bleed down thing. I can't find a check valve anywhere but it has to have one so what i am thinking is somehow they incorporated it into the top of the OEM fuel pump assembly ( sealed case ) I have replaced the fuel pump in the assembly, I don't have the dough or the want to replace the whole assembly. i was thinking maybe if I put a check valve in the line between the pump and the top of the assembly it would fix the problem, I wonder though what kind. It has to accommodate the right amount of fuel and it also has to be small enough to fit in the line without ruining the bend and binding it up when the assembly is compressed to seal the ring on the tank. this is yukon denali 6 liter vortech and the fuel pressure in the line will be 50+ to 60 pounds. Got any ideas on the check valve? today i am pulling the unit again to see if there is a check valve where I think it is ( ac delco help line has no freaking clue OR they just wont tell me) it;s possible if there is a valve there in the top that its gummed up wide open or something.
It's built in the pump. If the pump works great don't change it. If there a leak you should find it and fix it. Safety first. ask your mechanic if you don't know anything about mechanics. take care.
toolman talal yeah i just saw a video explaining the mechanics of the airtech pumps, i am sure the rest are very similar with the check valves. after seeing that, i am thinking it has to be the top of the pump to the underside of the top of the assembly. so thats my next thing. i am pulling the assembly and testing back flow from the line inputs to the pump top. mechanics are funny around here, I'm thinking i should go into business, they dont seem to know anymore than I do and they charge crazy prices for guessing.
Leisure suit Larry you should subscribe to (schrodinger's box ) channel in youtube it's great place to learn vehicle diagnosis . i am just a diy . take care .
toolman talal Turned out to be a Pin hole in the corrugated line inside the assembly. found it by hot boxing a cigg and blowing real slow , smoke into the fuel line IN side. replaced that hose and I got my pressure back. no more bleed off.
