Tex95Z

My Car is a 95 Z28 LT1.

The car will start with starting fluid, it will idle very poorly. Fuel pressure is 38 PSI @ idle, However pressure tends to wander while idling. Getting good spark. Ive tested the injector plugs with a noid light, all good. Fuel filter is new, regulator is used but came off a running 96 Caprice. What else can I check?

Injuneer

Does the idle improve as the engine warms up?

Tex95Z

nope

Injuneer

Has this problem developed all of a sudden, or has it been getting worse over a period of time?

It will be normal for the fuel pressure to "wander" while idling, if your idle is not smooth. Rough idle means wandering intake manifold vacuum, and the regulator adjusts the fuel pressure based on manifold vacuum.

Tex95Z

It happened suddenly, right after I adjusted valve lash.

Guest47904

Why did you adjust valve lash??????

Tex95Z

Sorry its a rebuilt engine from a 94, and the dowl pin was too short. so I had to do a cam swap before i put the engine in. (the cam is stock from a 95)

I set lash before i put the engine in but i didnt realize the lifters needed pumped up, so the valves where too tight.

After the valves where adjusted it ran excellent.

I shut it down, then the next day i installed the exhaust (stock cat, stock muffler, pacesetter mids)

I tried to start it after the exhaust was installed but it wouldnt start on its own.

joeSS97

Do you have cat(s)?

Tex95Z

Yes i have 1

Tex95Z

*update*

ohmed injectors all between 12.6-12.9


oil has gas in it

Guest47904

That may only mean that it's pumping fuel but not igniting it, obviously.

Do a compression check

If that's ok check spark.

Tex95Z

I have not done a compression test, I will do that this morning.
Are you thinking that the valves still may be too tight?

i have tested for spark, it seemed good.

when I tested for spark i tested #1 cyl. I also took off the valve cover to see when it was sparking, it was sparking when it was supposed to. not sure how to measure the amount of spark though?

Tex95Z

I used shoe box's guide for the test, All plugs removed throttle propped to WOT.


the results of the compression test are as follows


1---220 2---180

3---182 4---182

5---200 6---190

7---195 8---190


what should I be looking at next?

Also i changed the oil this afternoon. there was about 2 + quarts of raw fuel mixed in.

P.S. compression tests suck really bad with pacesetter mids

Tex95Z

If I had a few fouled plugs would these symptoms occur? Im pretty sure at least 4 plugs are fouled. Is there any way to test the actual plug?

96 mikez28

i would be double checking your intake manifold for vaccum leaks