CJ7 Will Not Fire

[Guest]

TBI 258 Cranks and cranks and cranks. Nothing. Will not fire. Again its throttle body injected and just cant quite seem to figure out whats up.

Things ive replaced.
Fuses and relays.
ICM
Battery

Things ive checked with a tester and visually
Injector power
Ignition relay for the ecm
Fuel pump
Fuel pressure. Howell reccommends 9-13 psi im at 11

Any suggestions on where to go next are greatly appreciated.

[spunebil]

Spark at plugs?

[Guest]

No clue.

[Guest]

Service engine soon light installed with the tbi came on. Made it home and its been sitting dead.. I need a gm obd port scanner so i can read whats goin on.

[Guest]

Like spune said. You need to check for spark. Easiest way is insulated pliers and holding the plug. Or go to the parts store or harbor freight and get an inline spark checker.

I need a gm obd port scanner so i can read whats goin on.

OBDI or OBDII?

Where are you located?

[Guest]

No spark from the distributor and no spark from the coil. Replaced the coil and still nothing. Gonna try a new cap and rotor tomorrow..

[Guest]

Heres the info

Chassis: 1984 Jeep CJ7
Drivetrain: AMC 258 T5 Trans
Electric fuel pump, Howell TBI kit


Synopsis. Driving home one night Aftermarket Howell Service engine soon light came on. Turned the CJ off for the night and went to start it up and nothing happened. Just cranked and cranked so i rode my bike to work that day.

Things i fixed: Replaced the distributor cap, plug wires, rotor, ignition module and starter solenoid.

Things i checked over: Coil, condenser, transmission neutral saftey switch, checked for spark, (which i now have)

Places i have controlled power to: Ecm, Starter, starter relay, fuel pump relay, injectors, coil, distributor.

Aftermath: Motor cranks on carb cleaner but dies after 1-2 seconds
Cant seem to fit the pieces together from here.. Hopefully that cleans the thread up
Thats how the CJ sits right now.. Crazy right? Now bring on the opinions and what not.

[Guest]

Sounds like fuel... or lack there of. Check fuel pressure at the rail.

[Guest]

I dont have a fuel rail. i have a throttle body injection system.. Im thinking the crankshaft position sensor may be bad.

[Guest]

Pretty much an engine needs three things...

Spark (you said you have that)
Air (we'll just assume it isn't parked in a vacuum chamber)
Fuel (you said it will run on carb cleaner which means everything else seems to be working you just don't have a fuel source.)

You need to check that fuel is reaching the intake. If it has fuel pressure is it coming out the injector?

[cjmoon]

it doesn't have a rail but should have a y-splitter that goes to two injectors on the TBI. I didn't think TBI had a crank position sensor maybe the tach signal or something like that? that lets the engine know it fired and is running? what about battery? what is hte voltage sometimes computers are finiky at low voltage

[Guest]

Yeah its got a tach signal wire. From the chilton schematic its white. I dont think its hooked up. Maybe thats the problem. As for the y split, it just has one pressure hose coming up from the pump and it runs into the tbi unit and it seperates the gas to each of the 2 injectors..

[Guest]

Howell emailed me saying they think im having a voltage problem. Guess i have some digging to do.. The main body harness is grounded out great. The other ground to the block from the negative terminal is good. The last one is in question. I have a ground from the neg terminal to the firewall. dont know why but i got it that way.. Paint is still there and everything. Alternator is bad as well. Il make a new ground from the block to the frame today and see what happens.

[cjmoon]

Alt is bad? that could fix all your problems as the battery gets lower the computer starts to have more trouble. take the grounds off and clean them up. not sure what your method is for good/bad, but tight doesn't always mean good and clean. Just a thought

[Guest]

Alt is bad? that could fix all your problems as the battery gets lower the computer starts to have more trouble. take the grounds off and clean them up. not sure what your method is for good/bad, but tight doesn't always mean good and clean. Just a thought

The alternator is definately bad. I got the jeep started and running today. It was the tach sensor wire. It was unhooked.