1981 VW Rabbit Pickup wont idle after sitting a 6 months

1852 Views 9 Replies 4 Participants Last post by ORCoaster, Sep 3, 2019

cedarhill

Discussion Starter · Jun 10, 2019

I have a 1981 VW Rabbit Pick (1.6) up that needed a battery so I let it sit for a season. When I installed a new battery and cranked it, it smokes really bad, is skipping, and wont idle. The smoke out of the tailpipe is a dusty type black. I thought that it may be an injector so I took them out and noticed that one injector has more of the smutty black than others, so I replaced it. It didn't work. Any help?

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briano1234

· #2 · Jun 10, 2019

Moving to the General forum as it was in the DIY/FAQ section.

I would suspect that you have a IP timing issue as that is what usually causes black smooty issues, as well as glow plugs that may have gone bad and not all cylinders are up to temp.

Skipping is a sign of air in the injector lines as it is also a sign that one or more cylinders aren't getting the proper fuel.
on the clear line are there air bubbles? Old diesel can grow stuff, so Diesel does get old, You may want to use ATF or a Oil product in the fuel to Lube it and to clean it out of growth, as well as replacing the filter.

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cedarhill

Discussion Starter · #3 · Jun 11, 2019

I ran some fuel cleaner through the lines but it didnt immediately seem to help. I said earlier that it was skipping, but realized when I cranked it this time that it is more like loping. I have a short video that I tried to upload but the site wouldn't let me. Is there anyway I could get that video to you?

BTW, thanks!

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briano1234

· #4 · Jun 11, 2019

Add about a pint of MMO Marvel mystery oil to the tank. Then you may want to borrow a dial gauge and set the ip timing.

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sgnimj96

· #5 · Jun 11, 2019

This may not help, but is worth checking - very easy only takes a 17mm wrench and some brake cleaner or equivalent,
Spray the area clean with brake cleaner first.
Take the OUT bolt off and make sure the tiny hole in it is not plugged up. There is a screen inside the bolt, but just one tiny hole that ALL the fuel flows through to get out of the pump. Poke it with a tiny wire, spray it out backwards and replace. Easy
That hole is super small so to make pressure in the pump, but if it's clogged diesel will not circulate (and air cannot escape).

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cedarhill

Discussion Starter · #6 · Jun 12, 2019

Thanks man, I'll do that. I'll have to look u the ip timing in the shop manual; not familiar with it. I'd love to get it running right and either drive it or sell it.

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sgnimj96

· #7 · Jun 12, 2019

Another easy test is: remove the return outlet fuel hose, replace it with some temporary tubing to direct fuel into a suitable container while it runs.
The injection pump should flow out a bit less than 1/2 quart of diesel in one minute at idle. Less than that means the fuel pressure regulator needs adjusting (not so important) or there is something blocking the flow (might be very important) like serious restriction in the fuel line in from the tank or the pump's out bolt is clogged.

Fun Fact: restriction(s) in the line from the tank often make bubbles show in the fuel tubing going into the pump, this is from the high vacuum from the pump pulling hard to get fuel. It will actually suck air in through good hose connections on the inlet side of the system. Also it's possible for it to suck air in through the seal in the front of the pump. This is why you need clear fuel hoses in and out of the pump.

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cedarhill

Discussion Starter · #8 · Jun 12, 2019

I'm going to try to make some time to work on the problem this weekend. I'll let you know.

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cedarhill

Discussion Starter · #9 · Sep 3, 2019

I'm finally getting around to working on the rabbit again. I never cleaned the screen in the pump so I've got to try that, but when I went to crank it before working on it, the fuel had to be bled back to the pump. I cranked it, shut it off, and an hour later it had to be bled again. Dont remember it doing this before.. any suggestions?

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ORCoaster

· #10 · Sep 3, 2019

You sir have an airleak in the system somewhere and the IP is draining because of it. Since you didn't take the OUT bolt off I am thinking seals on the pump since it has been sitting for awhile. The front seal or the ones on the cold start lever might be going. Could also be that big one on the back head area.

You might try doing a tighten on the fuel filter and in bolt. Go ahead and take that OUT bolt off and clean the screen. Just remember that those thin copper washers should be checked for smooth surfaces and get heated with a torch till they turn blue. Let them cool and reuse.
All the thinking I can muster today. Been on a hot roof doing shingles all day.

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