2nd Generation Specific (1986-1992) 1986-1992 Discussion including performance modifications and technical support sections.

Runs really bad after warmup

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Old 07-02-13 | 04:32 PM
  #26  
arad99's Avatar
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1990 T2
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From: Weirton WV
Originally Posted by satch
So you got 22psi w/the gauge inline or did you just not post the dead headed numbers?
When I first checked it, the fuel pressure was 25psi in line. Then I wanted to get the max pressure from the pump. That was the 22psi, dead headed.
So, I decided to check the voltage at the pump, which showed 5 volts across the black and red wires. Now I get 0.0 volts across the red and black wires. The jumper is on the yellow connector.
I'm not sure why I was getting 5 volts before and 0.0 volts now. Something changed.
Old 07-02-13 | 06:37 PM
  #27  
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From: Central Florida
red and black are not the correct wires.

black is ground at the top of the tank
black/white is 12v pump power

red is signal to either the low fuel light or the fuel gauge, i forget which is which.


i have also seen people wire up pumps to the red wire on the bulkhead, but the pump probably wouldn't even run wired that way.

Last edited by RotaryEvolution; 07-02-13 at 06:39 PM.
Old 07-03-13 | 12:12 AM
  #28  
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From: Weirton WV
Originally Posted by RotaryEvolution
red and black are not the correct wires.

black is ground at the top of the tank
black/white is 12v pump power

red is signal to either the low fuel light or the fuel gauge, i forget which is which.


i have also seen people wire up pumps to the red wire on the bulkhead, but the pump probably wouldn't even run wired that way.
Thanks Ben. I didn't look them up, I just assumed red & black.
Old 07-10-13 | 03:58 PM
  #29  
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From: Weirton WV
I finally found the problem. I had checked the fuel pressure several times and the pressure was always around 31 psi with very little drop off after 5 minutes. But, I always checked it after the engine had cooled off a little. Last night I checked the fuel pressure right after it had been running really bad. The fuel pressure only showed 25 psi and it started dropping quickly.
The problem was the fuel line going from the primary injectors to the secondary is soft right at the top fitting and when the engine gets really warm the fuel line expands and allows gas to spray out dropping the fuel pressure and starving the secondary injectors.
I haven't actually put the engine back together and tried it out but it seems to make sense. Should be ready for a test drive tomorrow.
Old 07-10-13 | 08:01 PM
  #30  
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From: Markham
just curious, but couldnt you smell that?i mean thats quite a bit of fuel being sprayed out for someone not to atleast catch a wiff of that... anyways good luck!
Old 07-11-13 | 08:03 AM
  #31  
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From: Weirton WV
Originally Posted by Logitikes
just curious, but couldnt you smell that?i mean thats quite a bit of fuel being sprayed out for someone not to atleast catch a wiff of that... anyways good luck!
Yeah, you would sure think so....... right? I did see it spray but evidently that is not the problem.
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