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I seem to be a Harbor Freight shill this morning. For $20 (-20% with coupon), Harbor Freight will sell you a fuel pressure gage you can hook up to the Schrader port on the driver side fuel rail and look for yourself. May have to pick one up myself today. That, and watch my tach while cranking the engine for longer than I like...
I seem to be a Harbor Freight shill this morning. For $20 (-20% with coupon), Harbor Freight will sell you a fuel pressure gage you can hook up to the Schrader port on the driver side fuel rail and look for yourself. May have to pick one up myself today. That, and watch my tach while cranking the engine for longer than I like...
Thanks for the heads up, I think I’ll try that. I went on line to harbor freight and I only seen one for $90.00 . If you go there let me know if you find one cheaper. Thanks again for your help !
As BigGun had mentioned F/P should be 58 psi on a '99...I didn't even pick up at that number...DUH !!...my '01 is 55-62 (non supercharged) and 50-62 (supercharged).Ok, we have a new pump and is it an aftermarket or OEM ??...something like a pump I's stick to OEM...if it is a "good" pump and that's key here and we have the correct fuel filter/regulator we now have to look at power and grounds. let's see if we have a clean ground at G-401 which is the ground for the pump (rear frame rail aft of rear upper control arm). There might be high resistance on that circuit...Sir, I don't know if you do your own maintenance but you can try that. I'd ask the guys who did the pump install why you got it back with low fuel pressure...TAKE IT BACK !!...show them minimum F/P is 58 psi. might be an incorrect diagnosis...I'm not sure if 50 would cause a long crank time...20 yes, 50 maybe. If you want to try to check the current draw of the pump you can pick up one of these ammeters...they are pretty cheap and easy to use and you can at least check the pump current. Say EVERYTHING checks good...now we have to go back to the tank and start troubleshooting there. Could be a bad check valve in the fuel feed rear pipe. OUCH !!!
Hi Rob, I went out and got a pressure gauge from h.f. I made sure a the threads were taped up so the wasn’t any leaks from gauge. I turned the key to on position and there was no reading on gauge. Turned key back off then back on and the gauge jumped up to 58-60 and I started the engine. Pressure held steady at 58 while running, turned car and key off the pressure dropped down to 0, turned key Back to on position, the gauge jumped to 58 then dropped down to 0. Started to crank the car, fuel pressure rose to 58(while cranking) and the car started. All this with new fuel pump. Fuel filter/regulator and a fuel pressure damper. No smoke when starting the car either. Thanks again for any info you can give me
Does it read the same thing with the key on? What does it read after starting?
I bought a gauge from h.f , hooked it up turned the key to on position, heard fuel,pump kick in but gauge didn’t move, turned key back off then turned back on for the second time and the fuel guage jumped up to 58 then I started the car. The gauge was holding at 58 while running but when I turned the car and key off the gauge dropped to 0. Started car a second time (fuel pressure rose while cranking) then car started and dropped again after car turned off. Car does not smoke when starting and always starts on the second crank. Has new fuel pump, fuel filter/regulator and a fuel injection pressure damper. Thanks again for any advise you can give
Hi James, not sure of those readings, might take it to another shop this week and have them check out the fuel pressure. It seems that it always takes to 2 times to start. I turn key to on position, here the fuel pump kick on then off then I crank it for a second or two then turn the key back off then back on again, I hear the fuel pump kick back on and off for the second time and the it starts right up. That tells me it’s probably a fuel problem, maybe a bad or cheap aftermarket fuel pump( was told fuel pump had a reverse flow check valve built in it ) but I’m guessing the fuel system is not getting a good prime ? Thanks again !
I hate to get involved in these things because all I can do is speculate....
That said. I had a similar issue with my car years ago. Car would start, but it would carry on and stumble, 400rpm idle super rough, sometimes die. Start the car back up, everything was ok and not another issue. Happened for 2 years (not every time for sure). Car would crank sorta slower than I thought was normal, even with a new 78 series battery and cables.
Final solution came when I replaced the STARTER, yep, starter, with a new GM Delco one. My conclusion was the PCM takes a voltage sample-and-hold when you first go to start and uses that as a reference point for many things thereafter. If that sample was low, then the thresholds for your sensors are all off. Car runs like crap. My take was the weak starter causes more voltage drop on the starting system than it should and throws off everything else. Once the new starter was installed, I had 4 years and never saw that again.
Not saying this is it, but I see these threads so often here and seldom does anyone ever come back and say they found a solution. It's all guessing. If it were me, I'd blow the $160 and eliminate this possibility. For full disclosure, I've also never seen where anyone else ever bought the starter and tried it. But I've seen tons of threads go dormant without an answer.
Hi Rob, I went out and got a pressure gauge from h.f. I made sure a the threads were taped up so the wasn’t any leaks from gauge. I turned the key to on position and there was no reading on gauge. Turned key back off then back on and the gauge jumped up to 58-60 and I started the engine. Pressure held steady at 58 while running, turned car and key off the pressure dropped down to 0, turned key Back to on position, the gauge jumped to 58 then dropped down to 0. Started to crank the car, fuel pressure rose to 58(while cranking) and the car started. All this with new fuel pump. Fuel filter/regulator and a fuel pressure damper. No smoke when starting the car either. Thanks again for any info you can give me
Hey Dave !!...well at least you started getting yourself some diagnostic tooling !!...whether you start the car and then shut it down or just turn the key on to get your 2 second prime the fuel pressure should not drop to zero. With all the parts that have been changed I believe all that's left is either a leaking fuel injector or the check valve in the fuel feed rear pipe...that's the only 2 things I can think of...if someone else knows of any other components chime in...to troubleshoot you can disconnect the fuel line at the fuel injector rail (I took a quick pic of it disconnected...you'll need a 3/8 inch fuel line disconnect tool...any auto store has them) and use an adapter that has a shutoff valve (pic enclosed) to seal off the fuel rail from the rest of the system...shut off the valve and if the pressure drops it's an injector....you can get one on E Bay...another way and probably easier is to just pull the injector rail off as one unit and place a rag under each injector or a pan to let the fuel dump into it...you can see which injector is leaking once the key is turned off...if that's good it's probably the check valve....a little more risky but that's the only 2 ways.. Even though you said it didn't smoke on startup I would still want to check for a leaking injector... if the injector isn't leaking I'd say it's the check valve...I believe you have to change the entire fuel
line !!
I bought a gauge from h.f , hooked it up turned the key to on position, heard fuel,pump kick in but gauge didn’t move, turned key back off then turned back on for the second time and the fuel guage jumped up to 58 then I started the car. The gauge was holding at 58 while running but when I turned the car and key off the gauge dropped to 0. Started car a second time (fuel pressure rose while cranking) then car started and dropped again after car turned off. Car does not smoke when starting and always starts on the second crank. Has new fuel pump, fuel filter/regulator and a fuel injection pressure damper. Thanks again for any advise you can give
I was typing while you were posting this. So before it held pressure, but now it does not? That's interesting...
I hate to get involved in these things because all I can do is speculate....
That said. I had a similar issue with my car years ago. Car would start, but it would carry on and stumble, 400rpm idle super rough, sometimes die. Start the car back up, everything was ok and not another issue. Happened for 2 years (not every time for sure). Car would crank sorta slower than I thought was normal, even with a new 78 series battery and cables.
Final solution came when I replaced the STARTER, yep, starter, with a new GM Delco one. My conclusion was the PCM takes a voltage sample-and-hold when you first go to start and uses that as a reference point for many things thereafter. If that sample was low, then the thresholds for your sensors are all off. Car runs like crap. My take was the weak starter causes more voltage drop on the starting system than it should and throws off everything else. Once the new starter was installed, I had 4 years and never saw that again.
Not saying this is it, but I see these threads so often here and seldom does anyone ever come back and say they found a solution. It's all guessing. If it were me, I'd blow the $160 and eliminate this possibility. For full disclosure, I've also never seen where anyone else ever bought the starter and tried it. But I've seen tons of threads go dormant without an answer.
Speculate all you want because that’s what we do here most of the time !!...yes, most of the time we never hear what the fix is..I think from now on I’ll tell the OP... whatever your issue is it’s NOT a blown fuse...if you don’t have the technical ability beyond that I won’t even waste my time explaining how to diagnose !!
Hey Dave !!...well at least you started getting yourself some diagnostic tooling !!...whether you start the car and then shut it down or just turn the key on to get your 2 second prime the fuel pressure should not drop to zero. With all the parts that have been changed I believe all that's left is either a leaking fuel injector or the check valve in the fuel feed rear pipe...that's the only 2 things I can think of...if someone else knows of any other components chime in...to troubleshoot you can disconnect the fuel line at the fuel injector rail (I took a quick pic of it disconnected...you'll need a 3/8 inch fuel line disconnect tool...any auto store has them) and use an adapter that has a shutoff valve (pic enclosed) to seal off the fuel rail from the rest of the system...shut off the valve and if the pressure drops it's an injector....you can get one on E Bay...another way and probably easier is to just pull the injector rail off as one unit and place a rag under each injector or a pan to let the fuel dump into it...you can see which injector is leaking once the key is turned off...if that's good it's probably the check valve....a little more risky but that's the only 2 ways.. Even though you said it didn't smoke on startup I would still want to check for a leaking injector... if the injector isn't leaking I'd say it's the check valve...I believe you have to change the entire fuel
line !!
I think it might be that rear feed pipe with the check valve. Do you know of a way to check that line and check valve ? any idea what the Part number might be for the line and check valve ?
I think it might be that rear feed pipe with the check valve. Do you know of a way to check that line and check valve ? any idea what the Part number might be for the line and check valve ?
I’d check the injector first !!...you can get the shut off adapter on eBay...p/n J37287...cheap if used. Don’t know the line/check valve p/n !!
I think it might be that rear feed pipe with the check valve. Do you know of a way to check that line and check valve ? any idea what the Part number might be for the line and check valve ?
I’d check the injector first !!...you can get the shut off adapter on eBay...p/n J37287...cheap if used. Don’t know the line/check valve p/n !!
I think it might be that rear feed pipe with the check valve. Do you know of a way to check that line and check valve ? any idea what the Part number might be for the line and check valve ?...this is for a 2001 !!
This is my fuel pump module...the fuel feed rear pipe has the arrow...you connect the adapter ( the aft is also 3/8)
here after you disconnect the line !!
This is my fuel pump module...the fuel feed rear pipe has the arrow...you connect the adapter ( the aft is also 3/8)
here after you disconnect the line !!
Hey Rob, I was told there was a reverse flow check valve built in the fuel pump, is there another check valve built in the fuel feed line ?
Hey Dave !!
I don't know if this is your daily driver but if you can wait till next week and want to use my adapter I can send it down your way...I won't be home till Friday...on vacation...don't want you to misdiagnose this problem without being 100% sure...let me know !!
Hey Rob, I was told there was a reverse flow check valve built in the fuel pump, is there another check valve built in the fuel feed line ?
Hey Dave !!..that I'm not 100% sure about the pump check valve...you have the check valve built into the rear feed line...I just sent you a reply if you want to borrow my adapter !!
09-09-2018, 09:17 AM
Knock on wood.