93 jimmy starts but turns over for ever

[taylorman]

My 93 jimmy runs fine but it turns over for ever before it starts. It's had a good tune up recently. The fuel pump was changed recently. I don't know what to do. I'm fairly mechanically inclined but this one has me stumped. I love my 4.3l and would like to keep it in tip top shape but I can't figure this one out. Any help would be greatly appreciated.

[MT-2500]

Check for good hot blue spark to 2 or more spark plugs.
If that is good check fuel pressure for being up to specs.
What engine and what engine code and mileage/
Fuel filter? What kind of plugs did they feed it?
MT-2500

[taylorman]

Originally Posted by taylorman

My 93 jimmy runs fine but it turns over for ever before it starts. It's had a good tune up recently. The fuel pump was changed recently. I don't know what to do. I'm fairly mechanically inclined but this one has me stumped. I love my 4.3l and would like to keep it in tip top shape but I can't figure this one out. Any help would be greatly appreciated.

This is a 4.3L w vin with a cpi. It has 135,000 miles on it. I put new plugs in with the gap at 35 thounandths like my manuel said. My fuel pump in only two weeks old but that doesn't necissarily mean it's working properly. The only code I found besides 12 was 28. What the hell is that. Neither one of my books show what 28 is. Also it has good spark on all 6 plugs. Puts out quite a jolt as I found out accidently.

[taylorman]

Originally Posted by taylorman

This is a 4.3L w vin with a cpi. It has 135,000 miles on it. I put new plugs in with the gap at 35 thounandths like my manuel said. My fuel pump in only two weeks old but that doesn't necissarily mean it's working properly. The only code I found besides 12 was 28. What the hell is that. Neither one of my books show what 28 is. Also it has good spark on all 6 plugs. Puts out quite a jolt as I found out accidently.

The plugs are Autolites.

[MT-2500]

Code 28 is a trans code solenoid problem but not for your truck.
Is trans working ok? if so clear code and see if it returns.
It is time to get a fuel pressure gauge on it.
Hard to start.
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.
On yours it is 55/61
Cold start should be 55/61 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 55/61 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.
MT-2500

[taylorman]

Originally Posted by taylorman

The plugs are Autolites.

with the ingition on pressure reads 61 psi. Once pump kicks off the pressure instantly drops to 0. With it running cold the pressure holds at 52 at a idle. The fuel filter and pump are only two weeks old.

[taylorman]

Originally Posted by taylorman

with the ingition on pressure reads 61 psi. Once pump kicks off the pressure instantly drops to 0. With it running cold the pressure holds at 52 at a idle. The fuel filter and pump are only two weeks old.

There are no visual leaks in my fuel lines. It's probably either in my tank or in the cpi unit itself. Personally I hope it's in my tank. Much cheaper fix.

[MT-2500]

You need to start looking for that fast leak down.
DO THE REST OF THE TEST.
Pinch off return line and check pressure.
Post back full pressure.
And watch for leak down with return pinched off.
If so pinch off inlet line between pump and fuel pressure gague when pressure comes up and watch for leak down.
If that cures the leak down it is in tank pump or tank hose or damper if it has one..
If it still leaks down you need to open upper intake and find the leak.
After the cover is off just turn key on and let fuel pressure come up and see where it is leaking off.
Watch injector AND INJECTOR UNIT and fuel reg and inlet lines for leakage.
MT-2500

[taylorman]

Originally Posted by taylorman

There are no visual leaks in my fuel lines. It's probably either in my tank or in the cpi unit itself. Personally I hope it's in my tank. Much cheaper fix.

Found my leak. The nut kit on my CPI Unit. Just going to change the whole unit. It'll save me work on down the road if I do. Thanks everyone.

[MT-2500]

Thanks for posting back and letting us know how it went.
We are glad you found the problem. And you are proably ahead replacing the injector unit while you are in there.

Good Luck MT