Thread: perplexed

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Hello, I live in Saginaw, Mi and have been assembling a kit car that uses a chevy 350 with throttle body injection. The car will start and run for a bit then shut off. It then may or may not restart.
Have changed out all the sensors, computer, distributor,and tried several different fuel pumps with no success. Checked out wiring, fuel lines, etc. Took it to another mechanic who changed distributor again and fuel pump. It ran fine for a day, then next time refused to start. Does anyone have a solution, I need help?

Body control module---theft control unit--do you have a key with a chip in it????????

I'm thinking theft control same as Jerry. Key to trouble shooting is go back to basics,does it loose spark,does it loose fuel pressure,does it loose injector pulse ?

Originally Posted by HWORRELL

I'm thinking theft control same as Jerry. Key to trouble shooting is go back to basics,does it loose spark,does it loose fuel pressure,does it loose injector pulse ?

Maybe a bit more information? You say 350 TBI, but you don't mention what controller. Did you use the OEM ECU and wiring harness, and if so did you send it in to one of the reputable geeks that strips out unnecessary programming and wiring? It sure sounds like an OEM security glitch is taking you out.

Originally Posted by rspears

Maybe a bit more information? You say 350 TBI, but you don't mention what controller. Did you use the OEM ECU and wiring harness, and if so did you send it in to one of the reputable geeks that strips out unnecessary programming and wiring? It sure sounds like an OEM security glitch is taking you out.

sorry guys, I'm using a motor out of a 91 camaro and harness, ecu and injection unit from Fuel Injection Specialties. There should be no antitheft issues involved. Fuel lines and filter have been blown out and checked multiple times, fuel pressure is more than adequate to keep motor running.

Originally Posted by Ski pro

sorry guys, I'm using a motor out of a 91 camaro and harness, ecu and injection unit from Fuel Injection Specialties. There should be no antitheft issues involved. Fuel lines and filter have been blown out and checked multiple times, fuel pressure is more than adequate to keep motor running.

Your words about fuel pressure are a concern. For that engine the fuel pressure is spec'd 9-13psig, and the warning I see is any lower or higher can cause problems. Do you have a regulator on the fuel, and have you verified pressure at the engine with a gauge? I'd be adjusting for 11psig, given the spec's.

I too would look at fuel pressure as a first step

Originally Posted by herbet99

I too would look at fuel pressure as a first step

yes, using fuel pressure regulator, verified with gauge at between 10-12 psi. at motor. all issues mentioned thus far have been double and triple checked and yet motor still won't reliably start or run more than a mile . now you are beginning to see why i'm perplexed. took intake off recently to see if there was an issue there but there is none. five different fuel pumps have been on the car.we have spark and we have fuel .

Where is your fuel pressure gauge at. It should be as close the the TBI as possible.
You state that you are getting spark. How do you know that it is getting spart when it quits running? What are you using to test that?

Is there a way you can check the ECU for error codes?

Have you talked to the people at Fuel Injection Specialties? It really sounds like it has to be an ECU problem, given everything you've changed.

Originally Posted by Ski pro

yes, using fuel pressure regulator, verified with gauge at between 10-12 psi. at motor. all issues mentioned thus far have been double and triple checked and yet motor still won't reliably start or run more than a mile . now you are beginning to see why i'm perplexed. took intake off recently to see if there was an issue there but there is none. five different fuel pumps have been on the car.we have spark and we have fuel .

this might sound really stupid and i do not know the correct terms but is your fuel getting enough air or is the air fuel mixture correct. that might cause your problem.

I just read back through your initial post, and it sounds to me like you may have fixed your problem of running for a short period of time and dying, but that your crank fuel (the injector pulse during crank) may be messed up. I have no idea how FIS does their programming, but for mine I have a base Injection Map, a base Spark Map, and then a handful of "correction curves" that apply modifiers to the two base maps for different things. One that I have continued to play with over time is Crank Fuel vs Coolant, which is basically the equivalent of the choke function on a carburated engine, but only active during crank, and on my engine small changes to that curve have drastic effects. There is also Injection vs Coolant, which only comes into play after the engine is started (above 600 rpm), and again is the choke function; along with idle speed vs coolant, which is your higher idle speed curve. Another that had to be tweaked is the Accel vs Coolant, and the Accel vs RPM which is the accelerator pump function.

Who do you have dialing in your ECU programming for you, or are you doing it yourself? Does Fuel Injection Specialties use laptop programming, or via some type of hand held?

It is perplexing. You said at one point that it ran fine for a day. What about your electrical setup? For example, how is your ECU grounded? Is it grounded directly to the battery? Perhaps you have a week electrical link somewhere.

good luck. I hope you solve your issue and I also hope you post that solution.

call to FI Specialties was no help they simply said to recheck everything the people in this forum said to check. Their unit is plug and play,. I am using their ECU, their harness and their TB Fi unit. Car went to an electrical specialist and he had it running right for a day but when it came back and was unloaded from trailer , it ran for a block, drove in garage and shut it off. Went to restart and back out again and refused to start. Changed plugs, was running lean when it would run, now running rich when it will run. Taking it back to electrical specialist as he had the most (but short) success. After verifying all electrical issues were fine the only thing he did was change distributor and fuel pump. I appreciate the suggestions but everything said so far has been done checked and rechecked. thinking about starting over with Edelbrock E street unit and asking for refund from FI Specialties as I believe the problem is a gremlin in their product.

well possibly a return is sensible, but electrical gremblims can be inherint in the vehicle----kit cars especially as the fiberglass(if used) (also on boats) doesn't promote happy grounding of circuits--- items I have seen in electric issues include poor wiring front to rear of vehicle, briaded hoses carrying the current, power coated parts bolted to gether, back feeds thru instruments, diodes dead, resistors---teflon tape on pressure/temerature fittings(biggie!!!!!!!!) sterio and car alarms, remote controls for everything from door locks, remote start, power windows, etc-------