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Engine will not start at times / low fuel pressure?

20K views 28 replies 4 participants last post by  Black1997 
#1 ·
New to this board as my usual hangout has gone very quiet.

My 97 Trans Am started to have issues where I had to crank at times up to 30 secs before it would start.

I finally bought a fuel gauge and hooked it up at the Schrader valve after I could not get it going at all and the battery was low from the cranking.

With the battery still weak I put the ignition on and it showed no pressure. Tried one more time and it went up to about 10 - 12 psi. Another try showed 0 again.

Fully charged the battery, ignition on and no pressure. Tried to start and it fired for a brief second then died.

Ignition on and about 10 psi and the engine starts, pressure goes to 33 psi on idle. Take it for a spin. Cruising pressure 33-34 psi and WOT drops to 18 psi.

Back in the garage turned it off and then ignition on with 38 psi. Leaving the gauge on to see if and how quickly the pressure drops. After two hours pressure dropped to 0. Pulled the fuel rail off and with ignition I only get about 12 psi. Pressure dropped back to 0 eventually but no signs of leaking injectors.

Based on what I've been reading, looks like my fuel pump is not performing / on the way out and should be replaced or do I need to look at something else, fuel pressure regulator?

Appreciate you help.

Rene
 
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#4 ·
At key on prime 43 psi is what you want. When idling 43 psi, under some running conditions pressure will drop some but 30 psi or below is never good. One way to test regulator is to unplug vacuum hose and pinch off while running. If low pressure goes up to normal reg is problem. Or if you smell gas when you take vacuum line off. Reg can fail one more way where spring inside has failed and allows fuel to go back to tank at all times. When you prime pump with engine off, fuel pressure should stay up for quite a while. If it bleed down quickly reg spring is usually bad. Finally fuel pump has a check ball in it that keeps pressure from bleeding off quickly. If it fails fuel can bleed back to tank but not as fast as bad reg spring.
 
#8 ·
Thanks guys for all the info. Funny I came across the trap door link back in 2009 and printed it in case I needed it.

Finally got to change the fuel filter today and it did not make any difference but I'm glad it's done. Fuel pressure still behaving strange and being way below 40 psi.

Next step is to replace the regulator which I should receive Thursday.

What is the best way to replace it, pull the fuel rail out?
 
#9 ·
So I changed the fuel pressure regulator today. Now the pressure on idle is lower than before with about 30 psi and below 20 psi at WOT.

What is even worse is the fact that the pressure drops to 0 when the engine is turned off??

Anything else I need to check or is the fuel pump my next step?
 
#12 ·
Finally got to cut the access hole in the trunk as per link above and replace the pump with a kit from Racetronix. Fairly straight forward job.

Upon ignition on, the pumps brings 45 psi and then drops just below 40. With the engine running the pressure is at around 38 psi on idle and when driving it goes up to 45 psi. So all seems right.

The only thing that puzzles me is the fact that the fuel pressure now drops instantly after shutting down the engine??? Any suggestions as to what it could be?
 
#13 ·
There are several reasons your pressure is dropping so quick. 1st suspect is there is a leak where pump hose attaches to metal pick up line. Next is the check ball in pump is bad, followed by an injector or injectors are leaking and allowing fuel pressure to leak down quickly, and finally pressure regulator could be stuck open just enough to bleed off pressure quickly, but not enough to lower pressure when running.
 
#14 ·
Well as I mentioned, I have a new pump and fuel pressure regulator.

Injectors were checked earlier and did not leak either. Connections in tank are solid.

Come to think of it after replacing the regulator the fuel pressure would drop a lot faster. Anything one can do to get it unstuck?
 
#16 ·
Have not installed the cover yet so I can pull the pump out a bit to check the connection.

looking from the back, the left connection is the return line, the second is a vent line, third is the supply line and forth I'm not sure what it is. Anybody can confirm that I'm correct and enlighten me on the forth.

If the pump connection is good I'll check the regulator out as this instant pressure drop started happening after I replaced it. Would it make sense looking at the return hose and see if any fuel returns there when the engine is shut down.
 
#17 ·
I lifted the pump out to confirm that the pump connection was solid. I then removed the hose from the first line from the left and fuel is coming back to the tank even after shutting down ignition.

With the ignition on, the pressure goes to 45 psi then after 2 seconds the pump stops and the pressure drops to 0 in less than a minute. So it looks like the regulator is leaking back.

Don't really want to crimp the return line to see if the pressure holds then so I will try to install the old regulator as it was holding pressure for at least 2 hours.
 
#20 ·
I have a 97 camaro that won't start for the first time of the day. It takes so many cranks in order to start, I leave ignition on for a while then switch off for a couple of seconds and then ignition on and then I crank it and it wants to start but it doesn't I gotta do that process like 3 times in order to start. But when it starts I can run it for as long as I want and it doesn't turn off. I can park the car and come back in an hour or 2 and it will start rite away no problem! But I take it to work and after a 8 hour shift the car won't star!
 
#21 ·
I checked the pressure with my friend and it reads 27psi at idle! Science I had been running the car when off the pressure read below 20psi! I replace the fule filter and added and additive and still getting the same problems! I would hate to drop the thank off to replace the fule pump because I think something else is leaking the pressure! Any help would be aprittiated
 
#23 ·
Well I did they easier tasks first, fuel filter then the fuel pressure regulator. As I mentioned the new regulator made things worse and the pressure dropped to zero right after turning off the engine. Actually went back with the old regulator.

From the several times I had the fuel rail removed, I knew the injectors were not leaking.

So only other choice was to replace the fuel pump which did the trick. With the old regulator the pressure still drops within a couple of hours after shutting down. But so far I have not had any issues starting the car after one day or a whole week not driving it. My fuel pump was on the way out as at times it would not even build up pressure at all.

If you don't mind cutting a hole in the back of the trunk, do yourself a favor and do the fuel pump switch that way, no need to drop the tank.
 
#24 ·
Marked layout with dimensions by earlier posted website


Cut the hole with a Dremel tool. Trickiest part is to get the two fuel lines quick connects disconnected.


Fuel pump pulled out


Fuel pump removed. I bought the Racetronic fuel pump kit which has all you need to replace the fuel pump. I also found some video's on YouTube which were very helpful in the process.

 
#26 ·
If your basing not cutting the trunk because your car is original, know this, these cars are common and always will be. They will never fetch those big pay offs you see on the Barrett Jackson auction. If you want a rare 4th gen get a firehawk, other wise you have one of many.
 
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