The Prelude sort of runs (with video!)

"duurtlang" (duurtlang) 10/27/2015 at 10:01 • Filed to: None

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After a glowing post !!!error: Indecipherable SUB-paragraph formatting!!! about how we got the not-run-since-2008 ‘83 Prelude sort of running again for a few seconds, we tried again this week. With varying results. Some advice needed here!

Summary of last weekend

The car had spark, but didn’t get any fuel. I found out it was the fuel cutoff relay. I bypassed it with a piece of electrical wire. The resulting continuously pumping fuel pump resulted in the carb dumping fuel into the location where the removed air filter needed to be. A bit of a safety issue, but a proof of concept. The car fired/ran, sort of, for a few seconds. We stopped it because of the fuel leakage.

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Having a parts car around helps. Technically the car we’re fixing up now will be the parts car eventually, but let’s no nitpick little details. I got the fuel cutoff relay from the second mk2 Prelude we have sitting in a garage. The difference between the two was immediately clear.

These are the two fuel cutoff relays from both vehicles. The rusty one is the broken one. The car we’re trying to get running had a fluid leak in the interior because the roof mounted antenna was absent for the 7 years it was parked outside, resulting in a bit of moisture getting into the interior, on the floor below the clutch knee of the driver... Hopefully we won’t run into any other electric gremlins as a result, as I did see some rust under the dash.

Under dash view, when having your head aginst the pedals, with the fuel cutoff relay seen in the top middle (black plastic square in white holder). The rust is clearly visible elsewhere. The car has been more moist than we had initially expected.

Inside of the broken relay. Nothing obviously broken. Replaced it anyway. The iron oxide on the car can hardly be missed. This is the rear window and the trunk. I believe a zombie apocalypse theme would fit this car best. It is going to compete in a beater rally. Every piece of patina that doesn’t interfere with the operation of the car or its ability to pass German inspection will stay.

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So we tried starting it. The video below is the first time since a week ago we tried it, and last week were the first few seconds of combustion done in that engine since 2008. So, basically, this is the first time it has run in 7+ years.

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At the end of the video you can hear it finally idles quite decently. Right after the end of the video we switched it off.

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This was last Saturday. Then, on Sunday, we tried again. Nothing. A single fire here and there, but it never really ran. The weekend before, with the bypassed relay, you could hear the fuel pump tick continuously at a high and constant frequency. It now ticked very occasionally and erratically, even with a bypass in place. My conclusion: some kind of blockage between fuel tank and the carburettors, resulting in a fuel pump that can’t overcome the pressure. A clogged fuel line or fuel filter probably. Can anyone confirm? Or is it likely something else? The car had ancient gasoline in the tank, but we did add 5 liters of fresh high octane gasoline. On Sunday we added a second 5 liters.

Plan for next weekend

Next weekend: 2 weeks from now. Anyway:

Replace lots of parts. We’ll start with the fuel system related ones.

fuel filters, front and back

flexible fuel lines

air filter

spark plugs

engine oil plus filter

brake fluid

spark plug cables

timing belt and serpetine belt

battery (will get one from one of my stored-for-winter Peugeots)

We’ll try to figure out if we need to blow out gunk from the fuel lines or if replacing filters and possibly flexible fuel lines will be enough.

That’s it for now. Any kind of advice is welcome! I’m as novice as they come, I haven’t even replaced engine oil before.

uofime-2 > duurtlang 10/26/2015 at 15:02

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After sitting for 7 years, I’d give serious thought draining the fuel tank and giving it a serious cleaning, and probably go ahead and replace the pump while you’re in there.

duurtlang > uofime-2 10/26/2015 at 15:09

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The problem is that it’s a Honda, and an old and rare one at that. Getting parts is hard, Honda is a niche brand at best here. We haven’t found a source for parts numbers either. But good advice none the less!

uofime-2 > duurtlang 10/26/2015 at 15:15

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I don’t know that Honda, but fuel pumps are usually pretty standard units, which is to say they are often used across many models and even makes. So you may find it is not as hard as you think to find one.

Mattbob > duurtlang 10/26/2015 at 15:22

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This doesn’t look like any relay I have ever seen.. No coils, no contacts... Looks more like a FET and some driving circuitry maybe.... Upon further inspection, that 5P1M is an SCR. Hmmm, curious. I wonder what they are doing here.

duurtlang > Mattbob 10/26/2015 at 15:32

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I don’t know much about electronics. The circuit board is on the underside, of which I sadly don’t have any picture. It’s quite a simple thing really. If there’s power on the IG (ignition) a connection is made between the + to the FP (fuel pump). What all those individual components do is probably logical and simple, but I haven’t read up on circuitry. Like I mentioned; novice.

Here’s the other side, assembled.