'83 Ranger w/ Duraspark Conversion suddenly having issues

[Fords4Us]

I did the Duraspark conversion on my '83 Ranger last summer (with a lot of help from folks here; thanks again). It's been my daily driver since then, and until this past Friday it was running great. I was out running errands and all was well, when I pulled into a parking spot and turned off the ignition. The engine unexpectedly dieseled (continued to run for a few seconds before stopping). Hmmm. Went into the store, got my stuff, came out a few minutes later, and fired up the truck. Suddenly the ignition was sky-high, and I noticed a loss of power as soon as I engaged the clutch and tried to get going. Long story short, I had very high idle speed whenever I put in the clutch, but noticeable lack of power as I tried to move through the gears. The higher the gear, the more noticeable the lack of power.

We did some troubleshooting over the weekend and noticed that the distributor had drifted out of position (I had everything indexed from when I did the conversion). No problem - put the distributor back into position, fired it up one more time, idle speed had returned to normal. Turned everything off and called it good. Until today.

When I went to run errands again today, everything was where we'd left it over the weekend. Truck started right up, but as soon as I put it in gear and tried to pull forward, it died. I started to adjust the distributor again but at each possible adjustment, either my idle was too high or my power upon engine load was too low. I'm starting to suspect something else is involved. My first hunch is that a vacuum hose plug fell out somewhere, such that I no longer have the vacuum I should have throughout the system. I suppose I can categorically start searching for such a problem, but does anyone have any ideas for what else it might be? Full tank, no other performance issues prior to my sudden symptoms last week. Thanks all. You folks are the only reason that truck is still alive and kicking.
Kathryn

 

[bronco2fan]

So does it idle fine just sitting? If you rev it up in neutral there's no hesitation?
It doesn't act like it's missing or starving for fuel? Plenty of fuel if you manually work the throttle with engine off? Fuel pump healthy? No loose plug wires? No loose or corroded wires from the swap? Dis cap not cracked or fouled? Lots of stuff to check. Hope this helps

 

[Fords4Us]

It idles smoothly while in neutral, and the clutch starts to engage normally. It's only when the engine actually starts to "grab" and the truck starts to move that it has no power. It behaves almost as if I'm trying to start in 3rd gear - that same sort of feel.

I'll go ahead and test the fuel lines and even look at the fuel filter while I'm checking it tomorrow, along with everything else you listed. Anything else come to mind? I'm trying to get a laundry list tonight of everything to check. Hate to close the hood and then think of three other things to look at. Thanks all.

 

[Fords4Us]

Well, I think we're fixed and roadworthy again, with one caveat. I had my laundry list of stuff to check, and went out with two books under my arm, a bunch of printouts, a bottle of water, ready for a long afternoon of testing. Popped the hood, and decided to start by verifying all the vacuum plugs were in fact still in place. Whadyaknow, as soon as I started to look, I saw that one of them had partially torn through and fallen off. It was still laying right on the valve cover just in front of the distributor. Replaced that, fired up the old girl and she ran just as smooth as usual. I do believe that vacuum plug simply fell off once it had torn far enough along its length. Didn't even get my hands dirty.

The caveat is that I also am starting to think the fuel pump is not performing at its best. My driving style isn't particularly aggressive, and I rarely "step on it" for sudden increases in acceleration. After replacing the vacuum plug I went ahead and cycled the engine (in neutral) through some throttle changes. It did just fine until/unless I got really aggressive with plunging the gas pedal down. That would reliably cause the engine to bog down and almost stall. So, I have a mild fuel starvation issue lurking somewhere. That I can explore separately.

Thanks again to everyone on the forums. Y'all are fabulous, and This Old Truck (and her old-ish driver) are both very grateful.
Kathryn

 

[bronco2fan]

Glad you got it sorted out. Might be time for a carb rebuild? Good luck and thanks for letting us know what it was.

 

[alwaysFlOoReD]

Does the carb have a fuel filter at the inlet? Check and replace if so. Also check if there is a filter elsewhere, usually along the frame.

 

[chewy012]

Not seeing it now, but the only reason I'm viewing this post is because a picture of Denzel in training day popped up on my news feed associated with this.

Anyone else?

I did not read any of this post, and i am on beer #8

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