Strange idle after 200 mile trip... (1 Viewer)

[QuietMike]

Took my '87 (stock 2F) on a 400 mile road trip this weekend (200 miles each way), and experienced some wierd stuff going on at idle. Here's the story:

I was running late on my way down, so I gassed up and drove straight there without stopping. After 200 miles of interstate driving (speedo at approx 65 mph on 31 in tires - around 3000 RPM), my engine wouldn't idle once I got off the interstate. I had to keep the RPMs up to keep from stalling (which I did a few times at stoplights). Parked the truck for 6 hours, got back in and it did the same thing. Drove 2 blocks to my hotel and left it overnight. When I cranked it up the next afternoon, there was no problem and it hasn't done it since, including when I got back home after driving the 200 miles back.

What do you think the issue is? Considering I got 16.2 miles/gallon on the way down (I couldn't believe it either), I think the engine is tuned pretty well. Idle typically sits at around 700-800 RPM.

Thanks for your help!

 

[ellington12]

quietmike,

when it stalled after getting off the interstate, was it difficult to restart or did it fire right up?

 

[dmede808]

There are some emissions things that get activated only with a warm engine. If one of the vac lines in these sytems is leaking it would only show up after the vehicle had warmed up. EGR is one of them I belive, and will kill your engine at idle. Get an emissions manual and check your vac lines.

A hot carb can also cause this problem I think (vapor lock), so if your carb fan isn't coming on after a long drive check that also.

 

[QuietMike]

Thanks, guys. It fired right up after it stalled with no problem at all, and my carb fan works like a charm. The engine didn't appear to get any hotter than when I'm doing my daily commute (5 interstate miles), but I do have a little of that temp gauge/fuel gauge flicker that's pretty common so it's hard to know precisely where the engine temp is.

I just figured she got mad at me for running so long without giving her a break...