Having problems with your 1998 GMC Safari ?

99 Tahoe engine cranks, wont start

\015 99 Tahoe engine cranks, have spark on two cylinders I have checked, I can hear the fuel pump and was able to get gas out of the fuel line on top of the motor when I checked it. ran fine three days ago parked it and now it just wont start.\015 Posted / edited by AnonymousUser on : 10-12-2018

Answers :

You need 3 things.
\015\012Compression
\015\012Good hot blue spark to all plugs.
\015\012Good gasoline and proper fuel pressure. 63-64 lbs.
\015\012If you have all 3 then move on to injector pulse to all injectors.
\015\012I think each injector is on a separate driver on that one.
\015\012Check for pulse to all of them.

You may be weak on fuel pressure . even a couple of lbs low on a cold start will cause a no start.
\015\012Double check cold start cranking fuel pressure. If under 63-62 lbs you have problems.
\015\012one test is to give it a squirt of carb cleaner not starting fluid. If it starts then you have a fuel pressure problem.
\015\012Run the full fuel pressure test and post back pressures.
\015\012Here is the guide lines on testing.
\015\012Hard to start cold.
\015\012Check cold start fuel pressure.
Check engine running fuel pressure.
\015\012Check engine running on the road fuel pressure.
\015\012Then shut it off and watch for fast leak down.
\015\012Pinch off at rubber part or block off return line and check full pressure.
\015\012Later V6 and V8 gm engines should have 60-66 fuel pressure.
\015\012Cold start should be 64-65 lbs of pressure.
\015\012If you do not have full fuel pressure on a cold start the injectors will not squirt fuel.
\015\012Do not leave home without it.
\015\012Engine running should be 60-66 lbs pressure depending on engine load.
\015\012Full pressure with return pinched off should be 75-85 or more.
\015\012And if it has a fast leak down after shut off you have a leak.


The 75-85 is only a check on the capable full pressure of fuel pump.
\015\012If you can not find the rubber return line check full pressure by\015\012plugging return line or just or the true full pressure can be taken\015\012direct at the end fuel filter.
\015\012What are the pressure readings that you have done.
\015\012What are your cold start pressure readings?
\015\012Post back what you have.


The other thing to that is common is the (ICM) under the distributor cap. There is a breather screen on the bottom of the distributor that get's clogged with dirt causing condensation promoting corrosion, this was gm TSB for replacing the cap and rotor to make sure it's clean.

Good luck and hope this helps. Merry Xmas.
Repair Help & Product Troubleshooting for 1998 GMC Safari

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