87 Honda Accord revs high with no accelerator input

My 87 Honda Accord has acted funny for awhile. It has been very intermittent for the last 2 years until this weekend. Since Thu it does this everytime it is driven.

When this happens the car starts good. It then runs rough, kind of bumpy and I know what is going to happen. After the car runs for 5-10 minutes like this it will accelerate uncontrollably. Granted I am accelerating the car as I go from start to go, and up hills, but when I let my foot off the gas, the car either remains at 3000+ RPM or it starts to rev up there on its own with my foot off the gas. It’s like the throttle is stuck. So I stomp on it and it goes to 4000+ RPM and stays there. Sometimes it comes down, sometimes not. Usually after 15 minutes it would go back to running normal. The past 4 days it is constantly this way.

A few facts. Car is not fuel injected to my knowledge, I don’t see injectors. The alternator light is on and my radio was cutting out this morning, windows sluggish, I think the alternator needs replacing. I don’t know if this has anything at all to do with the problem of revving.

I have thought that the throttle cable is sticky but it usually runs well and this was very intermittent (go months between episodes) for the past 2 years until the last 4 days.

Any ideas?

Thanks in advance,


The 1987 Accord came with both a carburated and fuel injected induction system. If your Accord, indeed, has a carburator, that might be your problem. That carburator has primary and secondary throats. Most of driving is done using the primary side. When you need extra power i.e. more mixture flow than the primary can supply, a vacuum diaphragm pulls open the secondary throttle plate. Since the secondary throttle shaft is not activated that often it can get gummed up and stick open which will give you high RPM and unintended acceleration. Usually a few sprays of carburator cleaner on the secondary throttle shaft at both ends will loosen things up and cure the problem. Alternately, a carburator rebuild might be necessary. If you have a shop look at this carburator, try to keep the original carburator i.e. have your existing carburator rebuilt as a parts store replacement rebuild may not have the correct calibration you car requires.

Hope this helps.

Thank you Researcher,

As it turns out, I took it to the shop because the Alternator also needed to be replaced. The shop, and my Chilton’s and Haynes manuals all said the left front axle has to be removed or removed from the steering knuckle at least. Well, when they went to do it, they found they didn’t need to remove the axle. That’s why I had it there.

Anyway, I asked them to look into the situation. What I found was that the choke was closed at all times. When I manually opened the choke, the RPM’s came down. Not to acceptable levels but came down. The throttle plate was clearly closed. I could not understand why the car idled at 3000 RPM with both the choke and throttle closed.

The shop found a break in the intake manifold gasket resulting in a large vacuum leak. Normally this would bog the engine in my experience. In this case, it created more airflow and somehow pulled more gas with it.

Unless they were lying to me, they replaced this gasket for a pretty penny and the car runs pretty good now.

I’ve never seen anything like it. I’ve had no trouble with it the past 3 years I’ve had it and I hope no more troubles with it.

Thanks again for your help. What you said is very logical and was where I was heading.