Got Rabbit trouble.

Models manufactured from 1975 to 1984

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Got Rabbit trouble.

Postby Trond on Jul Sun 29, 2012 12:44 pm

Hey everybody, I’m new to the forum and having trouble with my MK1. Big Sky Euro was recommended as a font of knowledge and good people.

The car is an 82 rabbit, (not sure of displacement, pretty sure it’s a cis car, oh yeah if you haven’t guessed, I’m pretty much an ignorant noob when it comes to anything more than changing fluids or replacing mechanical processes)
I bought it not running from the previous owner, who had replaced the head gasket pulled ac, unplumbed the heater core, and who knows what else. Before that I think it may have been something of a field car, since it is from out in cardwell. When I got the car, it would crank, but not start-- turns out the plug wires had gone back in the wrong order, making me a little leery about how well this went back together.

Now it will start but not run. It turns over right away, and runs well for a moment then dies out. If you gas it right away, and then hold a tiny bit of throttle pressure it will settle down into what seems like a passably healthy idle. Then the revs will ramp up wicked high for a second or two accompanied by what sounds like an unnaturally loud induction whistle, then settle back down to a lumpy anemic idle, and die. You can get it to run pretty much indefinitely by feathering the throttle, gassing it a little when it starts coming off the surge. Seems like the more it runs, the better, but the symptoms remain basically the same. Smells like its running a little rich, but I dunno.

I’ve checked all the vacuum lines, and they seem to be in good shape, no noticeable damage, or leaks. I’m going to try to disconnect the cold start injector and see if that makes a difference, but honestly I’m pretty much at sea. Is the fuel press spiking? (I don’t have a gauge) is it a vacuum issue? What the crap?!

Any advice would be appreciated, or even thought I’m sure this will be frowned upon in a DIY community, would anyone here be willing to look at it for me? I’m not trying to take advantage, but I’m out of town (Bozeman) 4 to 5 days a week, the car is parked on the street so working on it isn’t a casual exercise, and I have visions of the city towing it while I’m away.

Thanks everyone
Trond
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Re: Got Rabbit trouble.

Postby YASHA7FOLD on Jul Sun 29, 2012 5:37 pm

Look for leaks in and around your fuel block.
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Re: Got Rabbit trouble.

Postby Checkers on Aug Fri 03, 2012 6:36 am

I'm around all weekend and can have a look homie.
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Re: Got Rabbit trouble.

Postby Mikewire on Aug Fri 03, 2012 10:10 am

Oh man,I missed this post. I have a lot of info about CIS, and that's all just from fighting with my Caddy's CIS fuel system. You can read my progress and what I did here: viewtopic.php?f=79&t=3117

Since it's an '82 and it's CIS, it's probably the CIS that's giving you fits. If you are unfamiliar with the CIS system, there's not much to it and it's very simple, but it can be a real b*tch. There's a fuel tank, pump, fuel accumulator, fuel filter, and then on the top of your air box there is a fuel distributor which then feeds the injectors. Pressure is regulated by a FPR on the front of the block, and it looks like a small rectangle with a plug and fuel lines coming out of it, and they feed/return fuel to the distributor.

Here's an overview of the Bosch CIS K-jetronic system:

Image

There could be a couple of things going on here. I'm going to assume your ignition system is OK since it will fire and run. You are running just the fuel coming from the cold start injector (a.k.a the 5th injector) which is why it will run, but only for a moment. It sounds like it's working as it should, so bypass working on it.

First things to check:

Do you have a way to check fuel pressure? If you do, check it at the outlet of the fuel filter. If not, that's ok you can check a couple of other things. Continue...

Do you have old gas in the tank? If so, drain it, and put a couple of gallons of fresh gas in the tank...
CIS does not like having gas sit in the components, so be prepared to clean up any old gas or varnish that's in the system.

Check the fuel flow to the injectors: Pull one injector. They are hard to pull, but do come out. It would be good to have new injector O-rings handy so you can replace them as they tear or break, and these old rubber rings do break easily. With the injector out, put the injector in a bottle or bucket to catch the fuel.

You'll need to temporarily bypass the fuel relay an give power directly the the fuel pump - one way is to wire the battery to the pump, or you can also make a jumper using two spade connectors and jump power at the fuse block. Anyway you do it, the pump needs to be running while doing this test. Use your best judgement here, and always work safely around fuel and electricity. Always have a fire extinguisher handy.

Moving on, pull the big end of the intake boot off (attached to the air box) and you'll see the round fuel plate. Get a magnet - put the magnet on the bolt in the center of fuel plate. Turn the power to the fuel pump on, and lift up on the fuel plate using the magnet. It should lift up, and fuel should spray out of the injector. If not, then you have more work to do.

Check your fuel distributor plunger: The underside of that distributor is a plunger that controls fuel flow to the injectors - it slides up and down inside the distributor, and is controlled by the amount of air coming into your airbox - that plunger tends to get stuck if gas dries and varnishes. Carefully remove all the fuel lines, remove the fuel distributor, and flip the distributor over and the plunger will be smack dab in the the middle - make sure it's not stuck and it can slide up/down freely with little effort.

Tip: While you have the distributor off, be sure to check the small bearing on the end of the arm, which rides on the bottom of the plunger. It should roll smoothly, and if not give it a bit of oil.

With that working properly, assemble it all back together and do the injector test again.

If that doesn't do the trick then you can move onto the injectors, a they may be clogged or have stuck pintles. Pull all four, and soak in carb spray for a few minutes. Then take some compressed air and blow it in through the inlet of the injector - it should spray out the carb spray and shoot air through the outlet. Assemble and do the injector test again.

If that doesn't work, then you'll need to definitely check fuel pressure at the fuel filter outlet. You may have a bad pump or a restriction in the fuel line somewhere.

Oh and, change the fuel filter. If it's clogged or restricted you'll have no fuel at all in the distributor, and they are inexpensive.

Ok, that's a lot to do, but it may help you get started. Remember to work smart and safe around fuel and fuel lines. No spark etc. and always have a fire extinguisher within reach.

Good luck!

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Re: Got Rabbit trouble.

Postby YASHA7FOLD on Aug Fri 03, 2012 12:36 pm

Well done sir.


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Re: Got Rabbit trouble.

Postby MT-Getto on Aug Fri 03, 2012 12:59 pm

Mike has just been through this :)

Here's my usual fix (aba on the rabbit rather than VR6):

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Re: Got Rabbit trouble.

Postby Mikewire on Aug Fri 03, 2012 2:14 pm

Haha rofl...it actually very simple but does take a bit of time to tweak and make sure everything is optimal.

VR6 swap is always an option, especially when you have a spare in the garage :ninja:

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Re: Got Rabbit trouble.

Postby Trond on Aug Fri 10, 2012 12:02 pm

Thanks for the replies everybody, especially mike for that great rundown, though I think mt-ghetto's tuning technique is probably a better match for my building resentment towards the vehicle.

I changed the gas and put in a little injector cleaner. Don't have any way to check the pressure, though its definately flowing well at least to the cold start injector, maybe even a little high because of the way its surging? Found that the line from behind the throttle body to the vacum switch was lose, but reattaching it didn't seem to make a difference.

Well thanks again, I'll start working down the list. But first got to find somewhere to park it while its apart- the city took my plates last week.
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Re: Got Rabbit trouble.

Postby Mikewire on Aug Fri 10, 2012 2:44 pm

Having solid consistent fuel pressure is key with FI, and CIS is even more picky.

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