Hello!
I have a 1988 Ram W100 that has a engine from a 1989 Ram van. The car runs and drives (and I daily it), but I do have a couple of issues related to electrical and poor accelaration.
In an attempt to chase down the accelaration issue, my first thought was to check the engine codes by counting the check engine blinks, but that's where I noticed that I have no check engine light.

This got me thinking if some of these problems might be caused by some differences between the Ram and the Ram van, or the different years (88/89'). Are there any major differences in wiring and/or the SMEC/ECU?

The original SMEC that was in the car was faulty and swapped out for a second unit, which turned out to be DOA. The third SMEC is supposedly from a Ram van, but I'm honestly not 100% on that.

 

If both engines are fuel injected (I know '89 was, don't know about '88 for sure) they ought to swap okay. Sluggish performance can be a number of things. I would first put a vacuum gauge on it and see what you are pulling. A healthy engine should pull 17-20 inches if vacuum. Your exhaust might just be partly plugged or the timing is off or any number of things.

 

Yes, both engines are fuel injected (I believe '88 was the first year).

I think I have a vacuum gauge, but where would I plug it in to test the vacuum? Isn't there like central/test point that I should take the reading from?

 

You should have a external fuel filter on that, If you have over 100K on it it's time to change it. I had a 90 that wouldn't want to accelerate and after changing the filter it was fine. The check engine light should come on as soon as the key is in the "on" position. Did you check the bulb?

 

The fuel filter *should be* new, but I actually ordered a new one last night. The car has been undergoing a pretty slow restoration since 2011 so I've forgotten at which point the filter was replaced (or at all). But I've only been driving the car since end of April.

I replaced all of the bulbs in the instrument cluster when I put it back in earlier this year, so the bulb *should be* ok. But at this point, I might as well re-check it. This is why I was thinking if the wiring could be different, since AFAIK the check engine wiring goes directly from the SMEC and to the dashboard.

 

I went out and did a test with a vacuum gauge. the vacuum reading is between 17-20" so it seems good. I plugged it into one of the vacuum ports on the throttle body (not sure if that's the right place, I haven't done this before).

But I did manage to capture a pretty good video of the issue I'm having:

https://www.youtube.com/watch?v=PTQMlQgbNSU

 

It looks like a partly plugged exhaust but sounds like fuel starvation. Is the timing set properly? Can you drop the exhaust off the headers or Y pipe? You don't have a mouse nest, probably, but you may have restricted flow through the cat. or muffler.

 

It does not have the original exhaust so there's a good chance it was hacked into place, i'm definitely going to check that. But, what specifically makes you think that the exhaust is restricted? (I'm genuinely asking; trying to suck up as much knowledge as I can).

The timing should be correctly set, it was done by the guy who did the swap for me. But I have a timing light so I'm going to double check that as well.

Like you're saying, this really feels like a fuel (starvation) issue to me. When I was recording the video above, the whole cabin/car reeked of fuel. But what is throwing me off is that the problem seems to be less noticeable after the car has had a chance to warm up. If I drive it for 20-30 minutes, the issue seems to more or less disappear(ish). But I don't have much experience with this so maybe that's expected.

 

Fuel leak, no doubt. When your engine is cold, the computer goes into open loop mode to inject extra fuel to warm the engine up. That's why you don't put a cooler thermostat in it unless you flash the computer. You don't have a choke plate. When the engine warms up, the fuel demand is less.Where is your fuel pump? Early fuel injection Mopars had it either in or near the fuel tank. Later ones were in the tank. I think you either have a leak or restriction in the fuel line. Either the pump, or the line from it. I've never really fooled with the early F.I. trucks. Earlier ones, a bunch. Later ones, a bunch there. I think the fuel filter replacement should be your first priority. If it's partially restricted, the pump will be dead heading and leaking then when fuel demand drops, it quits.

 

Yup, the fuel pump is in the tank. This seems very plausible, I'm going to start there and update the thread once I figure out the issue.

Thank you so much Grouch (and everyone in the thread)!