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Discussion Starter · #1 ·
A littl background motor is a 90ish gm tbi 4.3 with a stock harness modified to run the motor, only sensors cut out were egr and i think i'm running an auto trans computer in a manual.

Here's the story might or might not be important

I left my buggy sitting for 2 months, i went to start it up and with about 15 seconds of cranking it started. I went to restart it and it wouldn't start again, it was flooded, i pulled the injector harnesses off the injectors, started it on the fuel in the motor and then put the injectors back on, it would run then. My distributor was loose as can be. After much monkeying realizing my alternator wasn't working, and swapping in a different throttle body i was able to get the motor to run. It ran like a top for the 15 min. road drive to the trail and 2 or 3 hours of wheeling. Then i go to start it again and it's flooded and i have to do the pull the injector wires trick again. I had to do that every time i shut off the motor to get it to restart.

Here's what's wrong.

The motor won't restart unless you pull the injector wires off the injectors, get it to run without the injectors hooked up, and then hook up the injector wires once the motor starts running. The motor runs really rich on start upand will some times idle and some times runs to rich at just about any rpm's. I'm not tripping any codes or a check engine light. Where to i go from here? I've swapped throttle bodies, idle air contorls, coolant temp senders, spark plugs.
 

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Might not hurt to look at the fuel pressure regulator. Check the pressure in your rail. See if it falls withing specs or if its orbiting off the scale.
Dave
 
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Without an OBD scanner, it will be hard to tell what is wrong....

When I did my SBC swap into my CJ using a 93 5.7L TBI, it ran great at first, and then started running rich....it took a scanner to see that I was not reading my coolant temp sendor correctly, hence, it was staying in open loop and dumping too much gas in....cleaning the connector to the sensor solved the problem....

I have since purchased an OBDI scanner.....

Moral of the story....get a scanner....otherwise, your just doing shotgun troubleshooting......
 

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My CJ with the Howell TBI would have difficulty restarting if the engine died on me. The engine would essentially flood. My setup does have a flood mode where you hold the throttle all the way down. I could get it to restart this way, but it did take a while.

The problem that I had was that the motor would just "die" when coming to a stop. The RPMs would drop below about 400 and it would just stall.

Howell sent me a procedure where I had to drill out a plug on the Throttle body and then adjust the idle air mixture. This essentially raised the idle RPMs to about 700.

I don't know if your problem is related or not.

-- Mike
 

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[ QUOTE ]
Without an OBD scanner, it will be hard to tell what is wrong....

[/ QUOTE ]
Agree

[ QUOTE ]
....it took a scanner to see that I was not reading my coolant temp sendor correctly, hence, it was staying in open loop and dumping too much gas in....

[/ QUOTE ]
You too? Same here and a second vote for CTS. Try unplugging it. It will set a fault code and ignore it.

[ QUOTE ]
Moral of the story....get a scanner....otherwise, your just doing shotgun troubleshooting......

[/ QUOTE ]
Strongly agree!
 

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Discussion Starter · #6 ·
I don't have a scanner, i guess i could take a multimeter and check to see if the voltages are within check. Holding the pedal to the floor to put it in "flood mode" doesn't work, it starts to go but it just doesn't quite do it.
 
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The voltmeter might get you close...but you really need to know what the computer sees.......

Many auto supply stores will scann it for you for free....I bought mine off Ebay for $85
 

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The volt meter may give you an idea and it's worth a try. In fact my GM driveability manual says you may choose to test drive the vehicle with a digital meter hooked into the suspect circuit to monitor voltage. Although, any dealer will have a Tech 1 handy.

Are you sure you have the check engine light hooked up correctly? That engine should have an vacuum EGR selonoid which it will want to watch once the engine gets to temp. This would not cause the condition you describe, but if you aren't seeing any check light at all, something may not be right there. Unfortunately you have to run the engine to do the check on this.

The spec for the CTS is tighter than I thought. The GM manual suggests that you check for high resistance in the circuit if the ambient coolant temp is more than 5 degrees off either way. Unfortunately you can only read this with a service scanner. I also see a reminder to check the conections and especially grounds for the PCM/engine.

These two items are most prevelant in the intermittant/poor fuel economy/hard start section. Without a trouble code it's difficult to go further.
 

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Discussion Starter · #9 ·
Come to think of it i swapped cts when i was tightening down a ground and broke off the plastic connector on the cts. I've got a check engine light kinda hooked up, it's a running light (so i couldn't wire it exactly how it was wired from the factory) it's more an ignition on light but the computer still gets it's 12 volts. If i put a test light in the circuit with the aldl grounded it will flash code 12 and nothing else. Every now and then when it does run i get some hesatation just off idle. Could this be a timing issue?
 

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Step 1 - get the check engine light hooked up correctly - with the correct bulb. That alone can and will give all kinds of trouble.

The original grounds at the ECM - there were several - wire them up just like they were factory - don't just tie them all together and hook it to a screw under the dash. I've SEEN that not work. There were several running to different places separatly for good reason.

Then, after it's wired correctly try it again. If the same still happens:
Key Off - measure the voltage right at the injector - or use a Noid Light - do you see any voltage across it now?
Key on - now?
You should NOT.
You should ONLY see the Noid light flash while cranking and running.
 

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Discussion Starter · #11 ·
Grounds are in facotry locations at the back of the engine on the driver's side head and the front pass side manifold stud.

I just went out and messed with it a little more. Coolant temp sender is putting out around 5 referance volts with the engine off/ cold (well sitting in the sun, about 70* air temps). The motor didn't act flooded when i went to start it, i actually had 1 injector unplugged when i went to start it. I actually had to plug back in the injector wire to get it to start. The motor is warming up right now, i'll see if it will restart and what the cts voltage and if it wants to restart.
 
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