2QUIK6

On the '95, it has suddenly become hard to start when its cold or has been sitting for a few hours.
FP is about 3-4 years old Racetronix.
Plugs have about 10k on them
Injectors are the original 110k miles
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Put a fuel pressure gauge on schrader valve, its has 37# with vac line on and 42# with line off.
Turn motor off and the pressure goes to 0 pretty quickly, less than 2 minutes.
But will fire right up in less than a second if motor is warm.
When cold, I have cycled the key on/off several times till there was 40lbs of pressure and it still takes 8 seconds or so to start. So even though it appears the check valve in the pump is bad, that does not seem to be the cause since it will fire right up if warm, and take forever even if priming the fuel pump/pressure before trying to crank it.

This seems to have started acting like this over night...any other ideas?
Found several posts on this topic but no one ever had any resolution except for someone changing the ignition switch.....think that must have been a different problem though as I don't see where thats relavent for this issue.

Guest47904

Weak spark
Restricted fuel injectors
Plug gap widening
Or a combination of both fuel and spark have finally gone over the threshold.

Time for a cap and rotor and a professional on the rail cleaning of the injectors. I used to clean them that way until I dumped my LT1.

And yes your check ball is shot.

Injuneer

When the fuel pressure drops off rapidly on startup, it makes it harder to start.

If you have ruled that out, check the coolant temp sensor in the water pump houing to be sure its telling the PCM the engine is cold.

If not that, check for leaking injectors. When you go to start it cold, does it start any faster if you hold the accel pedal on the floor, and then turn the key to "start"?

2QUIK6

Doesn't seem to start any faster if the pedal is held to the floor.
Once it starts, I can turn it right off and it will fire right up even though the engine is still cold. But also remember, it will not fire up the first time right away even if I cycle the key on/off several times to prime the pressure in the rail...so that is why I'm ruling out that check ball being bad effecting it at this moment.
Opti is about 20k miles old and its a AC Delco, runs great when started all the way up to 6k rpms no probs.
Coil...hmm, its an MSD and is probably 5 years and about 35-40k miles oldm so it may need replacing.
I'm going to try to get some time to test where the leak down is occurring, could be an injector leaking out the pressure too as the FPR seems to be working fine since I have 40+psi with vac line off. I did just barely pass emissions this year.

Fred, what signal do I look for the CTS on DataMaster? Seems like the only temp given is from the sender in the heads.

2QUIK6

Ok I think I'm getting somewhere..see if this makes sense or would cause this...
I pinched off the return line and energized the pump, fp went way up to about 70psi, then pinched off the supply line at the soft line section with a pair of needlenose vice grips and a rag for padding...pressure was at 45psi when pinched off...
Pressure still dropped on the rail to 0 in less than a minute!!
So that only leaves the injectors to be stuck open....about to put the Datamaster on it and see where the numbers are as I just leaned out the program slightly after it barely passed emissions 2 months ago.

2QUIK6

Well stumped again.....The LTerm counts/BLMs are 135/135 in Park, and don't go outside of 127-131 in Drive at various cruise speeds....so there goes the stuck injector theory...now WTF is the pressure going down so fast with both lines pinched off???

rclearyiii

Just unbolt the fuel rails and lift the injectors up. Then pressurize the system and look for any leaking injectors. Have a friend there to cut off the car quickly if there is a significant leak for safety reason.

Guest47904

You don't have to try to run the engine to find a leaky injector. Jump the fuel pump prime connector.

Injuneer

It only takes a very tiny leak in a single injector to cause the fuel pressure to drop rapidly. That small leak may not be enough to affect the BLM's.

2QUIK6

Would it be enough to cause the hard to start issue when cold?

Injuneer

Loss of fuel pressure, prior to starting the car, will extend the cranking time. You are looking for the cause, and I suggested several possible causes. You ruled out the injector leak possibility, by looking at your BLM's. I'm just pointing out that was not conclusive. If the pressure is dropping off rapidly, from my experience, it makes the engine harder to start.

Dtimekw

Yup, my check ball is bad and if I wait too long after turning the key to "on", it extends my cranking time since the FP drops to zero after initial prime.

IMO, go with what Fred suggests. He's never steered me wrong and you will probably learn something along the way.....

2QUIK6

np, I will look into the injector leak first and correct that if some issue is found and then go from there. This was my daily driver, but as of Friday I will have a new driver so I can let this one be down for a while if it is the injectors rather than having to put it back together then order up some new injectors to take it back apart again.

2QUIK6

Ok, did that today, no leaky injectors found......sooo
I'm guessing that maybe the supply hose has ribs in it or something to prevent it from being pinched is why the pressure still fell off with them pinched off with vice grips..had them set all the way closed.

So, I'm going to pull the plugs next and check the wires and go ahead and replace the coil...then go for the pump if that has no positve result.
But..it did fire right up after putting the rail back on

rclearyiii

Rob..good luck on everything. Let us know how it goes.