12v auto loping in gear, stalls when hot

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BigB82789

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Sep 23, 2007
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Have a friend with a 12v auto. Complains that it lopes in gear and when it gets up to operating temp it will stall. It has gotten worse in the last week. Also when in D, if you try to power brake it, the throttle gets very stiff and it won't rev up.

I replaced the overflow valve with a Tork Tek with no change. Other than that it is all stock top to bottom, and front to back. I also bumped the idle up to 1000 in gear and AC on.

My thoughts are: delete the fuel heater, and check the tv cable. Any other ideas?
 
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I would say possibly a sticking plunger. Does he have a fuel pressure gauge cause a buddy installed a tork tek and the factory pressure was way off so we had to adjust it. This is just my $.02 goodluck.
 
Shut-off solenoid pulling all the way up? Is the woodruff key still in the shut-off shaft/lever?

What injectors?
 
Nope, just been out of town a couple days.

Shut off solenoid is completely intact and stays up. Injectors are stock.
 
The reason I asked about the woodruff key on the shutdown shaft was, we had a customer with similar problems. Truck would start and idle fine but did not run well much above idle. We checked the shut-off solenoid as usual and all looked good. Looked for other issues and none found. We decided to pull his pump and in the process found that there was no woodruff key on the shutdown shaft. The pinch bolt made it just tight enough to turn the shaft enough to start but it would not completely "open up". He had pulled the lever off the shaft and didn't realize it had a key in it when he put it back on.
 
So the plunger is sticking as it expands from the heat? How would I go about testing it. I would hate to have him buy a pump and not fix the issue.
 
BigPapa said:
The reason I asked about the woodruff key on the shutdown shaft was, we had a customer with similar problems. Truck would start and idle fine but did not run well much above idle. We checked the shut-off solenoid as usual and all looked good. Looked for other issues and none found. We decided to pull his pump and in the process found that there was no woodruff key on the shutdown shaft. The pinch bolt made it just tight enough to turn the shaft enough to start but it would not completely "open up". He had pulled the lever off the shaft and didn't realize it had a key in it when he put it back on.
Click to expand...

Where did you find a woodruff key to fit it? I lost mine here a while back :doh: and just cranked down the bolt that puts tension on the shaft. It has been working fine, but I would like to have another one for peace of mind. I checked a couple of hardware stores, they have the keys, but none that small.
 
We had one from a junker. I'm sure if we needed one we could get it from a pump shop or probably Cummins.
 
I bought an autozone woodruf key and just took my time and ground it to a perfect fit.
 
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