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90 1500 throttle body flooding


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richardlice
User

Mar 31, 2014, 6:04 PM

Post #1 of 18 (1680 views)
90 1500 throttle body flooding Sign In

1990 Chevrolet Cheyenne 1500 4.3 TBI 110k
i had to replace the motor in the truck because of a crank bearing problem. i found a used motor with 110k on it, i have installed the motor, my problem is that when i turn on the key the throttle body injectors wont stop spraying fuel like they are stuck WOT. i checked the TPS the ohms are a base of around 4 ohms and smoothly increase as you press the throttle with no dead spots. i changed the fuel pressure regulator, coolant temp sensor and the injectors still the same result sprays until i turn the key off


Discretesignals
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Mar 31, 2014, 6:24 PM

Post #2 of 18 (1668 views)
Re: 90 1500 throttle body flooding Sign In

If you unplug the electrical connectors from the injectors, do they keep spraying while your cranking the engine?





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richardlice
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Mar 31, 2014, 6:33 PM

Post #3 of 18 (1665 views)
Re: 90 1500 throttle body flooding Sign In

it stops when you crank with the wires on the injectors, it does nothing with them unhooked


(This post was edited by richardlice on Mar 31, 2014, 6:35 PM)


Discretesignals
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Mar 31, 2014, 7:03 PM

Post #4 of 18 (1652 views)
Re: 90 1500 throttle body flooding Sign In

Unplug the ECM and see if they spray. It is looking like a faulty ECM or it is somehow getting crank signals from the ignition control module with the ignition on (unlikely).





Since we volunteer our time and knowledge, we ask for you to please follow up when a problem is resolved.

(This post was edited by Discretesignals on Mar 31, 2014, 7:05 PM)


richardlice
User

Mar 31, 2014, 7:24 PM

Post #5 of 18 (1648 views)
Re: 90 1500 throttle body flooding Sign In

i unplugged both plugs on the ecm, nothing happens when i turn the key on, so would that mean the ecu is bad
Unsure


(This post was edited by richardlice on Apr 1, 2014, 4:29 AM)


Discretesignals
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Apr 1, 2014, 4:19 AM

Post #6 of 18 (1623 views)
Re: 90 1500 throttle body flooding Sign In

Unplug the distributor





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richardlice
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Apr 1, 2014, 5:07 AM

Post #7 of 18 (1616 views)
Re: 90 1500 throttle body flooding Sign In

when i unplug the dist. the fuel stops. if i plug in the four pin without the coil pluged in it still stops. when i plug in the coil the injectors wont stop.


Discretesignals
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Apr 1, 2014, 5:50 PM

Post #8 of 18 (1600 views)
Re: 90 1500 throttle body flooding Sign In

Let me get this right. If you have the ignition turned on and engine not running, the injectors will spray fuel all the time, but when you unplug the distributor connector they stop spraying?

Do you have the old distributor from the other engine?





Since we volunteer our time and knowledge, we ask for you to please follow up when a problem is resolved.

(This post was edited by Discretesignals on Apr 1, 2014, 5:51 PM)


richardlice
User

Apr 1, 2014, 6:01 PM

Post #9 of 18 (1597 views)
Re: 90 1500 throttle body flooding Sign In

yes with the key on fuel sprays, and the distributor is the old one(about a year old) from my bad motor that still ran when i pulled it (knocked like a booger) i have one that came out of the new motor but i didnt know how old it was so i used mine


Discretesignals
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Apr 1, 2014, 6:06 PM

Post #10 of 18 (1593 views)
Re: 90 1500 throttle body flooding Sign In

What you could do, as a test, is take the distributor from the engine you got and just plug it in. Then take a jumper cable and ground the shaft of the distributor to the battery negative.

Then turn the ignition on and see if your injectors are showering. Don't turn the shaft of the distributor or else sparks will be flying around.





Since we volunteer our time and knowledge, we ask for you to please follow up when a problem is resolved.


richardlice
User

Apr 1, 2014, 6:26 PM

Post #11 of 18 (1591 views)
Re: 90 1500 throttle body flooding Sign In

ok i took the old distributor and did like you said and the injectors dont spray but i hear a clicking coming from the two ovular black things, not sure what they are, on the passenger side of the firewall, the injectors also dont spray the first spray to prime like they normally did before when the truck ran before


richardlice
User

Apr 1, 2014, 6:30 PM

Post #12 of 18 (1589 views)
Re: 90 1500 throttle body flooding Sign In

oh and the fuel pump keeps running also


Discretesignals
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Apr 1, 2014, 6:41 PM

Post #13 of 18 (1588 views)
Re: 90 1500 throttle body flooding Sign In

Just curious, but did you install all your grounds on the engine? Make sure your grounds are clean and tight on the thermostat housing bolt. There should be some more grounds on the back of the cylinder heads. It is important to be sure that you have good grounds not only on the engine, but also from the engine to the body. Ground problems can cause all kinds of weird things.





Since we volunteer our time and knowledge, we ask for you to please follow up when a problem is resolved.


richardlice
User

Apr 1, 2014, 7:46 PM

Post #14 of 18 (1582 views)
Re: 90 1500 throttle body flooding Sign In

i checked all my grounds with a test light they all seem good, i have another harness from a 94 (will it work for a 90) should i try that?


nickwarner
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Apr 1, 2014, 11:55 PM

Post #15 of 18 (1574 views)
Re: 90 1500 throttle body flooding Sign In

Test lights don't need much current to run. Being able to light up shows continuity but can fail under load. Try hooking a jumper cable to a clean shiny part of the engine. Alternator bracket might be a good spot. Hook the other end to battery ground. See if there is a difference.


Tom Greenleaf
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Apr 2, 2014, 3:37 AM

Post #16 of 18 (1568 views)
Re: 90 1500 throttle body flooding Sign In

Spot on Nick. Test light isn't proof for this. If an LED and like them those don't take any power to light. Jumper cables make great test grounds which are everywhere. Battery neg to engine, again battery or then block to body metal and body metal to frame for some things too.


The existing straps can look OK but not be or got tugged or broken with an engine swap easily, T



richardlice
User

Apr 2, 2014, 3:55 AM

Post #17 of 18 (1565 views)
Re: 90 1500 throttle body flooding Sign In

just checked all four grounds with my fluke they are all right at 12 v (at the wire not just the bolt) not sure but Could there be a problem with the harness? also tried jumper wire to a good clean spot, no change


(This post was edited by richardlice on Apr 2, 2014, 4:35 AM)


richardlice
User

Apr 2, 2014, 7:35 AM

Post #18 of 18 (1554 views)
Re: 90 1500 throttle body flooding Sign In

i feel dumb after some deeper digging(and some daylight not a flashlight) into the harness i found a broken brownish wire under some tape, no fuel spray with the key on now, i believe that was the problem






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