The pump will bleed pressure, but over a matter of minutes-like 15 or so, not right away. Looks like a new pump is in order...

 

Just ordered a Racetronix Fuel System today from the WS6store. I should have it by Friday. Hopefully I will get a chance to install it this weekend.

I will let y'all know.

 

Exact same issue. Boiling down to one of 2 things for me.
1) Fuel Pump - I'll want and see what happens wioth your's
2) Injectors - Cheaper and easier to replace and I feel like this may be what it is. Been looking at these and it seems right http://www.speedinc.com/cont.cfm?cid=C0000845

I'll say this...I have had this problem for 5 years on my 98 Z. I'm simply fed up at this point and want to resolve it.

My setup is fairly stock, air filter to manifold upgrades, a catback and some performance tuning that was included with some of the PCM issues I had (for more on that all you have to do is ask as it is another rediculous ghost of a problem that was resolved)

I'm not one to just dump money into parts just for the hell of it, but my build has led me to put in the following all new parts:

NGK TR55 plugs
MSD 8.5mm wires
MSD Coil packs
PCV Valve
HP Starter
HP Alternator
0 Gauge Battery terminal wires
Fuel Filter
IAC
TB
Z06 MAF
Crank Sensor
Cam Sensor
MAP Sensor
IAT Sensor

and a host of other parts. Some went bad, some needed to be put in because of stereo, some I wanted to upgrade. I think it is safe to say we are narrowed down to a Fuel issue at this point.

 

You cutting a hole in the trunk or dropping the junk (axle, exhaust, tank, etc.)?

You should do the fuel pressure test-that'd be the cheapest/easiest thing to do above all...

 

You should do the fuel pressure test-that'd be the cheapest/easiest thing to do above all...[/QUOTE]


100% Agreed - On the way out to get the gauge now. I meant what I said from a labor perspective, but yes you are right overall. Any idea of what the numbers should be assuming the pump is A-OK?

Thanks!

 

i have the same problem with mine (im swapped) and have similar pressure fall off to 10psi like you guys do. hopefully you guys find a solution, i have a walbro pump, its like 3 years old but only started doing it with this motor.

http://www.youtube.com/watch?v=uuo57yox3sc

 

Was the motor a new crate or did you pick it up used?

 

used, only 14k miles though

 

I swapped out the fuel pump with the racetronix fuel pump and wire harness yesterday. The fuel pressure does not drop to 10psi anymore when the key is in the on position. It stays at 58psi everytime I cycle the key from off to on. When the car is running it sits around 60psi. It looks like this fixed the issue I was having, but I will keep my eye on it. I had a friend help me with the install and we ended up dropping the exhaust, disconnected the passenger side shock and spring from the axle and then dropped the fuel tank. I can't imagine doing this by yourself. It is definitely easier with two people, because the fuel tank gets heavy holding it up above your head when you are fooling with the fuel tank straps and bolts.

Those of you who are experiencing a similar problem I would suggest borrowing or buying a fuel pressure gauge that attachs at the fuel rail schrader valve. Check your fuel pressure with the engine off and turn the key to the on position. Then check it with the engine running. Check both several times and then post your findings to this forum.

Good luck.

 

Excellent update. Did you have to pull the exhaust out in any way or cut anything? Or were you able to unbolt it and slide it out? Did all this on a lift, jackstands? What would make the whole process less painful (aside from not having to drop the tank) lol

I went out to buy a gauge this weekend and the knuckle draggers at my local P3pBoyz do not have it. They might have had it in stock...but I am sure they wouldn't be able to find it. How do I know this you ask? -

Well when I told the guy basically, "I need a fuel pressure gauge for a GM car to check fuel pressure"
He asked, "What type of car?"
I responded, "Camaro"
He responded, " Camaro... Is that a Chevrolet?" Understandable right??? Well he said Chevrolet like this: "Shev-Row-Let" lololol

So I walked out before he found a way to sneak a Ford part in my car

Seriously though, 2 things on my end. If someone who has a better idea which fuel pressure gauge I should buy, whether it be on amazon, ebay, anywhere please shoot me a link so I can pick one up online and check my pressure.
2nd thing - I have a buddy who bought a crate LS1 couple years ago. Came with 28lb injectors (stock for 98 F-Bodys which I have) He promptly upgraded the motor and and needed to buy new ones before the motor was even run. So brand new he is going to loan them to me, they work I will buy em, they don't work, they just go back to him for use in something else so it isn't the end of the world.

Ideally I want to have them in by Wednesday/Thursday night that way I can flog the car over the weekend and see if the heat issue is resolved. Have doubts seeing as though the pump looks good so far.

 

Literacy fail on my end - Sorry got too excited when my eyes darted to the part where you thought it worked. However, any other suggestions on the process would be great.

 

My friend had the fuel pressure gauge but before I knew he had one I called around and Autozone had one to loan out. Check with them. It just a hose with a gauge on the end. The end of the hose should thread on to the schrader valve on your fuel rail. My car is a 2001 and I don't know if their is any difference on a 98. I don't think there is.

All this was done on a car lift. I have a flowmaster catback on my car and instead of cutting the exhaust pipe that flows over the axle we slide it off the y-pipe and let the curved section that goes over the axle hang on the axle. Disconnecting the right rear shock and removing the spring allowed the axle to hang low enough so that the exhaust would be out of the way making the fuel tank come out easier.

 

When I first started this thread I thought it was for sure a fuel pressure regulator, because the fuel pump was still pumping fuel. In my situation the fuel pressure was in the normal range, about 58psi, when the engine was running, but when the car was off and the key was in the on position it would not hold pressure. From what I understand the fuel pump has a check valve built into it that keeps the fuel that is in the fuel line from flowing back into the tank. It turns out in my situation that the check valve in the fuel pump was broke, but the motor was still pumping fuel. If it was a fuel pressure regulator, which is also located in fuel tank, then the fuel pressure would not be in the normal range when the car is running.

Bottom line, check your fuel pressure before you start pulling stuff off.

 

OK - So here is my update. It is limited, but it is one nonetheless. Got the fuel pressure gauge and put it on this weekend. Car was dead cold, put the gauge on and put the car to run. GM Manual calls for 55-60psi of fuel pressure and I am sitting pretty at 59psi. Now, I left the key in the run position for about 10 seconds and watched the pressure slowly drop to around 30-40psi and level off there. Is that OK?

I pulled up Junkman's manifold removal procedure as I had intentions of changing the injectors I was given to see if it solved my problem.

https://ls1tech.com/forums/generatio...n-dummies.html

I was pretty much dead in the water before I began. I bought the same "OEM" fuel line removal tool as in the 4th picture. It WOULD have worked, except the F-Body fuel line connecting to the rail is a little "shorter" and I can't get the tool around line completely. That was that and no injectors were changed. I have a buddy who owns a shop and has a low profile tool that will do the trick. Problem is I am flying out for work on Thursday, and unless one of us gets super ambitious in the next 72 hours I am not sure it is going to happen for a little while but we will see. Honestly, the whole removal is a joke, the biggest obstacles (for me) are getting that line off and my strut tower brace that needs to come off in order to clear the rails from the manifold. Will update on all this soon as I can. Bottom line on the injectors, got em brand new for free to test. Solve the issue or not the are mine for $150 if I want them so they are going in the car one way or another at least from a diagnostic perspective.

Circling back now, I am not sure my fuel pressure drop means anything at this moment. Like we all said, car starts every time when it is stone cold. It is the warm heat soaked starts that present the problem. Correct me if I am wrong, but that is when we want to see where the fuel pressure is at - when the car has been driven, has been up to normal temps for a little, and then has been let to sit. Then lets say an hour or 2 after it sits, go to start it, and the hard start is there.

Bet I can speak for most here when I say, All I want to do is blow off this work trip just to play with my car

Thoughts? Suggestions? Tips? Advice? - All are welcome. Please do tell me if I am doing something wrong, or should simply be trying something else.

 

New Injectors installed last week before my trip. Just got back a day ago. Car is 110% smoother to say the least. I Ohm'd out the old injectors and resistance was ranging from 11.0 -13.0 on all of em. Whereas the new injectors all Ohm'd out at 11.5. So gunna keep checking it for the next day or so and see if my hard start issue is resolved, but a cool byproduct of the swap (at least in my case) was a way smoother running car. Will keep updated

 

IAT heat soak also messes with how well it catches - timing
gets pulled and mixture is modified, away from what the
real situation needs.

Try this - put the IAT sensor in your pocket next time and
plug it in right before starting. See what happens.

 

Yea - funny you read my mind on the IAT deal as well. I looked through my parts pile the other day and found that I had bought a new one from GM and just never put it in. I am going to play with the hot IAT idea and see. Just went down to check the car, injectors didn't solve the issue. Like I said, made a great difference in drive-ability because mine were all over the board, but did not solve the issue. Going to roll with this for a couple days and see what it does. Test around, put the new one it, put the old one in, and keep trying. If I start the car without the IAT plugged in at a point when the hard start should happen (I can basically tell you when it will/won't happen as it is that predictable) will the computer just start it in closed loop and disregard that sensor until it throws a code? Basically asking if it is a real test to keep unplugging just before I start the car to see if it still does it.

 

Damn He's Good!!! Looks like a $25 IAT that I have been sitting on for 5 years may have solved this. That and its so damn cold out my car is cooling down faster than I can check it. v8fd3s - Might wanna pick one up and try it in your car and see. I'll update as I drive it some more, but hopefully this issue can RIP.