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-   -   Fuel/firing Problems with Fuel Injected TPI engine 87 camaro z28 (http://www.hotrodders.com/forum/fuel-firing-problems-fuel-injected-tpi-engine-87-camaro-z28-19250.html)

chevcamz28newbie 07-09-2003 06:02 PM

Fuel/firing Problems with Fuel Injected TPI engine 87 camaro z28
 
I am having some problems and dont know what the next step to do is. I have a 1987 camaro iroc-z z-28 TPI, 350 5.7L , I just bought it off a guy and it ran "ok" but i knew some work was needed to be right. First, the water pump was bad, so we changed it and then the starter went bad right after that(it was already giving us problems) so we changed the starter also. We changed the fuel pump and filter for kicks to make sure it hadent got any bad fuel, and put good fuel.the 4 front belts were also changed. We treated and changed the enigne/transmission oil and power steering fluid wich were all in serious need since the car had sat for some time, the guy claimed to have changed the engine and i talked to the original owner that my friend knew and he said his had a knock, and when we did have the other one running it seemed fine with no nocks . We checked the rotor / distributor cap and all were fine and then we checked to make sure all the spark plugs were firing, they were. We got down to the fuel injectors and they are spraying like they are supposed to, but my friend said that the spark plugs werent getting wet, and they were supposed to be, does anyone have any suggestions on what to check next?
thanks, Herschel

DoubleVision 07-09-2003 07:08 PM

you said you changed the fuel pump, did you bleed the air out of the fuel rail?

trees 07-09-2003 07:25 PM

Hmmmmnn. Sparkplugs in a running engine should never be wet. What kind of test were you supposed to be doing that would result in wet spark plugs? The 87 IROC is the first year of the 350 TPI, I believe, and it was a "batch fire" system. You should have 24# per hr injectors and your fuel pressure should be regulated to 41-43 PSI. You have completed a pretty logical sequence of checks and replacements to this point. Now I would check the fuel pressure with the engine running. Be sure the guage is hooked up before start and you disconnect after shut down. If pressure is good, then you need to read your engine codes. Auto Zone, Pepboys etc should be able to help you with this to see if you have some obvious problems. Then you want to look at your Throttle Position Sensor (TPS) You check it with an ohm meter and look for for _.4 to +.2 ohms at the engine off,idle position. Then move the throttle smoothly to the WOT position and back to idle, watching for the ohmmeter to increase/decrease smoothly with the throttle. This is the usual suspect for a poorly running TPI since it works a bunch for normal driving, especially city driving. Next would be your Mass Ai Flow Sensor (MAF) which is in the air inlet before the air cleaner. Then the last would be your oxygen sensor, which is a plug with wire (s) in the exhaust pipe just after the exhaust manifold. The above mentioned parts stores should be able to tell you if your system is in open or closed loop. It should be in closed loop. If it is in open loop, you need to replace the 02 sensor because the engine will run too rich in the open loop mode. There are two sensors that seldome fail and that is the inlet air temp and the coolant temp ( normally seperate from your coolant temp guage sensor). The MAF, 02 and TPS are expensive enough that you do not want to start replacing them unless you have a known failure.

Good luck.

Trees

Custom95Z 07-09-2003 11:49 PM

a lot of fuel injected engines have an extra lobe on the camshaft to run the fuel injection. I'm not sure about the TPI, but I know a lot of the MPFI and SFI applications do have this extra lobe. Depending on whether or not your engine does have this lobe and also depending on the mileage of the engine, your lobe may be worn down enough that the injectors are not firing in time with the intake valves opening. I hope that makes sense lol and hope you figure out the problem.

snkbyt 07-10-2003 12:52 AM

Think I would be checking the power and grounds at the computer. Just finished a 85 Corvette TPI that wouldn't idle and ran like s***T. The guys that put the engine in didn't connect the computer ground at the left rear cly head for the O2 and injector control curcuit. The Iroc is the same system except it uses 2 relays for the MAF sensor burn off. The spark plugs shouldn't be "wet" but light brown. You need a scanner to test this system to see what all is doing. Complicated system that goes into "limp" mode" if computor fails so you can get home. If it runs it isn't going to be cap, rotor, module problem. BUT in all the post you put up you never said what the symptoms were ONLY what you changed so need more #s on what readings of sensors and GEE what's it doing?? If they changed engine they forgot to hook a ground to computer.

snkbyt 07-10-2003 12:53 AM

forget the post about the extra lobe on the cam!!!! NO WAY

Custom95Z 07-10-2003 01:08 AM

I know for a fact that on the 3.4L Chevy engines, there's an extra lobe on the cam for the fuel injection. The 3.1 and 3.4 FWD engines also have this extra lobe. I'm not familiar with the TPI 350's. But here's one for ya...I have a 1995 Camaro with the 5.7 350 and the cam runs the water pump...there's no pully on the water pump. The distributor is also located below the water pump (over the timing cover) so ya can never tell about these newer engines lol sorry if I misled you about the extra lobe...I just remembered running into that when I was going to put a cam in my fuel injected 3.4 and couldn't do it with the fuel injection system still sitting on top...would have had to change out to TB or carb..anyway good luck with diagnosing the problem lol

snkbyt 07-10-2003 01:26 AM

Custom, better check out the 350's as the poat!!!! not the 3.4s.

chevcamz28newbie 07-10-2003 05:56 PM

Add on
 
Sorry, the car was running before but when we were working with it and changed the water pump it started to slow and almost completly idle no matter how much gas given, now it went from running to currently just turning over and not cranking, trying to fire up once after you start turning it over but after that, just turning over. We also changed out the computer on it and my friend checked the fuel pressure before we started taking things apart to get down to the injectors(what a pain just for the injectors) and he said the fuel pressure was fine...the fuel pump was checked before and put back but the ring somehow got dropped into the tank we got it out and went bought a new pump with new seal rings , the guy at autozone said that without the ring in place it would not let the tank become pressurized so this we changed along with the new pump. well just thought i would try to give some more info on this what we did maybe someone could get a better picture than i gave before. Like i said it was running and kind of started to slow then before it crapped out it was just barely wanting to go when you gave it gas, not sure why. Where the fuel vacuum line is above the injectors(in that area toward the inside of the car not the nose) when we took the top off , we werent sure if we did it or it was already broken but that vacuum line looked like it was already broken, but if it was broken before how would it have ever ran....any advice?

lippen3 06-12-2009 09:44 PM

injection problems.
 
yeah i have the 87 camaro too and its not firing. we changed the whole starter and ignition system in it. we've narrowed it down to the fuel injectors or fuel lines. its getting spark but i dont think any fuel to ignite. there is 0 pressure coming from the fuel thingy behind the plenum (where it should squirt out fuel or air depending). nothing...Could it be a leak in the fuel line?

DoubleVision 06-13-2009 12:03 PM

This thread is 6 years old.


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