'96 Jimmy SLT Starting problem

[Ratazc]

This starting problem is a little strange for me. It only happens in the morning
perhaps when its been sitting for over 8 hours...anyway....
It cranks over and over .... pause, try again ....almost starts .... pause
... I repeat this for some 10 to 15 mins ... then it starts ....
I thought it was the fuel pump at first, but if it was that ...why does it
start up...then go all day. Then happens again the next day.
I did notice that each day its taking longer for it to start....any suggestions
as to what to look for?

Thx.

[MT-2500]

Welcome to AF.

When engine is cold it needs full fuel pressure to squirt the injectors cold.
Even a couple of lbs. low can cause a no start cold.

Hard to start cold.
Check cold start fuel pressure.
Check engine running fuel pressure.
Check engine running on the road fuel pressure.
Then shut it off and watch for fast leak down.
Pinch off at rubber part or block off return line and check full pressure.
Later V6 and V8 gm engines should have 60-66 fuel pressure.
Cold start should be 64-65 lbs of pressure.
If you do not have full fuel pressure on a cold start the injectors will not squirt fuel.
Do not leave home without it.
Engine running should be 60-66 lbs pressure depending on engine load.
Full pressure with return pinched off should be 75-85 or more.
And if it has a fast leak down after shut off you have a leak.
Post back fuel pressure readings.

[blazes9395]

Get a fuel pressure guage on there and see what your getting when this is happening.

[blazes9395]

I was going to go into more details, but I thought i'd check to see if MT posted and yes he beat me to it, follow his advice....

[MT-2500]

blazes9395
If I had know you were answering it I would have let you have it.
But it is hard to resist a hard start cold problem.
Go ahead if you want to help him.
MT

[Ratazc]

Thanks for your reply.......

(w/ engine warm/hot)
With just ignition on I get 54lbs.
Kind of stays around there with engine on.
I shut off engine....pressure doesn't really fall.
I didn't understand that "pinch off at rubber part"....
I guess yo mean the bleed off tube?

So I need to check after it cools off...I guess tomorrow morning.

Do you think it may still be the fuel pump? I changed it last year...around
this same time. Then I couldn't even hear the pump running.

Again Thanks.

Originally Posted by MT-2500

Welcome to AF.

When engine is cold it needs full fuel pressure to squirt the injectors cold.
Even a couple of lbs. low can cause a no start cold.

Hard to start cold.
Check cold start fuel pressure.
Check engine running fuel pressure.
Check engine running on the road fuel pressure.
Then shut it off and watch for fast leak down.
Pinch off at rubber part or block off return line and check full pressure.
Later V6 and V8 gm engines should have 60-66 fuel pressure.
Cold start should be 64-65 lbs of pressure.
If you do not have full fuel pressure on a cold start the injectors will not squirt fuel.
Do not leave home without it.
Engine running should be 60-66 lbs pressure depending on engine load.
Full pressure with return pinched off should be 75-85 or more.
And if it has a fast leak down after shut off you have a leak.
Post back fuel pressure readings.

[Ratazc]

So with it cold ....reading on guage is the same. actually it has lowered to
50 lbs. After a long time I got it started again...while in idle needle jumps
from 50 -54. While accelerating it (in park)...it stays a constant 50.
I replaced the gas filter...same. Do those extra 6-12 lbs of pressure make
that much of a difference?

[MT-2500]

Originally Posted by Ratazc

So with it cold ....reading on guage is the same. actually it has lowered to
50 lbs. After a long time I got it started again...while in idle needle jumps
from 50 -54. While accelerating it (in park)...it stays a constant 50.
I replaced the gas filter...same. Do those extra 6-12 lbs of pressure make
that much of a difference?

Sure do.
Why do you think you are having cold start problems.
Even a couple of lbs low can give you a no start cold.
If you do not have full fuel pressure do not leave home without it.
MT

[Paul Hayes]

Originally Posted by MT-2500

Sure do.
Why do you think you are having cold start problems.
Even a couple of lbs low can give you a no start cold.
If you do not have full fuel pressure do not leave home without it.
MT

Hello, I have a 1996 Jimmy SLT and it is doing the exact same thing. Are You saying it is the fuel pump that needs to be replaced? Thanks for any response. Paul

[blazee]

Originally Posted by Paul Hayes

Hello, I have a 1996 Jimmy SLT and it is doing the exact same thing. Are You saying it is the fuel pump that needs to be replaced? Thanks for any response. Paul

Click here to start your own thread and someone will help you diagnose your problem properly.

http://www.automotiveforums.com/vbul...wthread&f=2072

[MT-2500]

Originally Posted by Paul Hayes

Hello, I have a 1996 Jimmy SLT and it is doing the exact same thing. Are You saying it is the fuel pump that needs to be replaced? Thanks for any response. Paul

Welcome to AF On your first post.

No I am not saying the fuel pump needs replaced.
I am saying check fuel pressure and if you do not have full fuel pressure do not leave home without it.

Please start a new thread on your jimmy and some one will help you.
Two different problems on one post will get you two different answers.
Just go to new thread and give us all of you info.
What it is doing or not doing and mileage and engine info.
Repair and tune up history helps to.
MT

[Ratazc]

OK so I finally replaced the fuel pump.....it starts now BUT the pressure is the same...54lbs...never gets up to the 60-66 lbs range.