Idle adjust

[JStraw]

Well, after 8 months and 15k miles of putting up with the fast idle it miraculously cured itself when I left work to go home yesterday. As soon as I fired it up I immediately noticed the all to familiar roar of 950 rpms was absent. I wish I had an explanation for it but, as I had thought from the beginning, it must have been something binding up on the inside of the pump. My linkage has returned to its full forward position instead of being about 1/4 to 1/2 inch away. I can't imagine a fuel gel being the cause but who knows. Know I got to reset my idle adjust and give the power screw a few turns

 

[tugboatphil]

Bob,



Just for the record, does the data plate on your pump say Bosch or Mopar? My 93 has the same problem and I was talking to a mechanic at the local Cummins shop. They don't do pump work, and I haven't gotten over to see those folks yet. But he pointed out that my pump had a Mopar plate, which meant that Chrysler had rebuilt it. Factory pump should have Bosch on it. He said the Mopar pumps are usually crappy due to them not wanting much power, resulting in more warranty claims.



Now how this would affect idle speed is beyond me, but it may be a common thread. My idle screw is also not touching.

 

[Bob Beauchaine]

TugboatPhil

My pump is a custom built pump - by Wentland Diesel in Milton-Freewater OR and is a Bosch pump



Bob

 

[JStraw]

Left for Atlanta after work Friday and at 167 miles into the trip I had to pass a slower vehicle. Put the pedal down and made the pass at 90 mph. When I let off it didn't decelerate like normal. It took longer. Put the transmission in neutral and... DANG... high idle was back. It stayed that way the rest of the 150 miles I had to go. I didn't use the truck again until it was time to go home today (Monday). Fired up with the high idle and ran that way until about 50 miles into the return trip. Now its back to normal. I'm miffed

 

[JStraw]

Its been over two weeks and my truck hasn't acted up So, I got a thinking long and hard about the problem. I had to rule out a mechanical problem on the grounds that they don't fix themselves when they break. It then dawned on me that this problem started to occure and occured every time that I filled up at a Tom Thumb/Citgo station. I continued to fuel up there for 6 months and just 'lived' with the problem thinking I would eventually need to change the pump. It wasn't until I started to fill up at Texaco/BP/Shell/Chevron that the problem was intermittant to "cured". Since the 25th of August I have strictly used these stations with no ill effects. It took 5 tanks of fuel and 3K miles on the interstate to bring it to the point its at now. I ran each tank down to 5 gallons remaining before refuels and changed the filter once. I also think that the increased speed of the pump to maintain hiway speed, along with good cleansing fuel, sped the goo removal that caused my heartburn. Time will be the true test but my confidence level is high

 

[Dieselman359]

Good Fuel

JStraw, good to hear that your fuel problem is worked out, I always stress to my buddy to buy at a truck stop or somewhere where they sell a lot of fuel at a reputable place. I changed the fuel filter in my other buddys Duramax ,and we saw quite a bit of dirt, crap in the filter. He like to bargin hunt and fill up at every mom and pop gas station, and it showed in the filter. :-{}