injector problems 85 vette
Thread Starter
Cruising
Joined: Jun 2006
Posts: 12
Likes: 0
injector problems 85 vette
Getting close to probleme, 85 corvette runs on only 6 or 7 cylinders. Fuel pump pressure is 35 lbs idle and 40 lbs over 2000 rpms. Checked all injector wires with light and they all function properly, all new tune-up. all wires properly installed . Injectors all come in at 18 ohms. Did fuel pressure leakdown to see if injectors leaked and pressure stayed at 35 lbs for over 20 minutes.
What i found is when i listen to injectors with stetoscope #4 and #7 do not click like others and when i unplug these 2 injectors idle does not change( still runs rough) and when i unplug other injectors engine idle drops dramatically thus running even rougher.
Would it be possible that injectors are defective after all these tests.
If so i will order new 24 lbs injectors , car is bone stock except for 160 thermostat and hypertech chip installed in 1987.
thanks for all your help and input
What i found is when i listen to injectors with stetoscope #4 and #7 do not click like others and when i unplug these 2 injectors idle does not change( still runs rough) and when i unplug other injectors engine idle drops dramatically thus running even rougher.
Would it be possible that injectors are defective after all these tests.
If so i will order new 24 lbs injectors , car is bone stock except for 160 thermostat and hypertech chip installed in 1987.
thanks for all your help and input
Le Mans Master
Joined: Feb 2006
Posts: 8,753
Likes: 9
From: Louisiana
I would suggest to pull all the plugs and look at them, especially #4 and #7. Make sure there is spark at each cylinder. I have done this by using a spare spark plug and pulling the wire on one cylinder at a time. Put the plug in the wire and hold it about 1/2" away from the exhaust manifold. Have someone hold the wire or crank the engine and you should see a spark. Do this on all 8 to rule out spark problem. The leak down tested good and shows that none of the injectors are leaking. The 18 ohm each must be confirmed when cold and hot as the resistance changes when the injector coils get hot, for a true test.
You say that you cannot hear #4 and #7 injectors clicking with a stetoscope. Can you feel them clicking with your finger? It is obvious that you don't have either fuel or spark on the two cylinders from you description. The spark plugs will tell you a lot.
You say that you cannot hear #4 and #7 injectors clicking with a stetoscope. Can you feel them clicking with your finger? It is obvious that you don't have either fuel or spark on the two cylinders from you description. The spark plugs will tell you a lot.
Thread Starter
Cruising
Joined: Jun 2006
Posts: 12
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First thing i checked for was spark and spark is perfect on all cylindres, also checked compression on both cylinders and they come out at 150 lbs. I found that plugs were a bit wet but obviously could see that they were not firring much. Hard to tell with new plugs and no street use.
Race Director
Joined: Jun 1999
Posts: 14,924
Likes: 9
From: Merritt Ils Fl
You have compression and you have spark but the cylinders don't fire. Kinda narrows the search down to the injectors. I assume the valve train is functioning. Compression test wouldn't necessarly confirm that. Certainly looks like you are in need of a set of injectors. I am confused as to why all injectors have the same resistance and two do not seem to function.
Melting Slicks
Joined: Apr 2002
Posts: 2,118
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From: St. Charles, MO Route 66 Corvette Club
If I had this problem and know what is stated in the above posts, I would do the following: 1. Go to NAPA and get a noid light to assure all injector harnesses are receiving a signal (voltage) from the ECM; 2. Remove the injectors and have them checked/cleaned. Rich Jensen at Cruzin Performance has a good reputation for this type of service. You may have a simple problem of clogged injectors.
Thread Starter
Cruising
Joined: Jun 2006
Posts: 12
Likes: 0
All injector wires were checked with noid light and all flashed, wiring is fine.
Had injectors cleaned a few times in last few years but problems keep coming back.
I am ordering new injectors tomorrow.
thanks
Had injectors cleaned a few times in last few years but problems keep coming back.
I am ordering new injectors tomorrow.
thanks
