# Some help...84' rabbit GTI



## RUwagen (Mar 3, 2010)

Gotta 84 rabbit GTI and ive been tryin to help my buddy get it rollin again....so it fires up and i got it to idle great, but everytime i try to give it gas and it bogs out, or dies. if i give it gas very slow the RPM's slowly will climb up, but not very well  We just put a new fuel pump on, timing is on, and i havent had much luck the last 2 days. 

Its got the 1.8 8v with neuspeed TB, Big Bore intake, TT full exhaust. use to be fast as f:beer:ck 

...Any feedback on ideas would be sweet guys, Thanks :thumbup::beer:


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## RUwagen (Mar 3, 2010)

And something i forgot to add is, ive checked for vacume leaks, and none i could find, checked upper and lower intake boots for cracks, and they were good.


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## scirockinit (Oct 16, 2008)

plug wires! also check grounds and distributor and coil!


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## Rabbitissimo (Dec 21, 2009)

Idle air o rings, injector o rings, manifold/gasket, air flow sensor plate location, height, and gasket, fuel distributor o ring (Between air box & fuel dist.) and every single vacuum line should be looked at. Check your engine grounds.
Even check your gas cap seal, (Should be pressurized) and oil dip stick and funnel!


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## Glegor (Mar 31, 2008)

Rabbitissimo said:


> Idle air o rings, injector o rings, manifold/gasket, air flow sensor plate location, height, and gasket, fuel distributor o ring (Between air box & fuel dist.) and every single vacuum line should be looked at. Check your engine grounds.
> Even check your gas cap seal, (Should be pressurized) and oil dip stick and funnel!


never seen a fuel tank that was pressurized in an old vehicle. it actually should be vented. there is a long black hose running from the tank to the passenger side frame rail up by the timing belt cover. that hose just dips into the frame rail..

remember, we are talking about an 84 vw here, not a 2004..

usually the only time a vehicle has a pressurized tank, is if the vent is clogged, and it went from cool to hot outside, then the fuel and air in the tank expand..


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## JoggerNot (Nov 6, 2009)

Glegor said:


> never seen a fuel tank that was pressurized in an old vehicle. it actually should be vented. there is a long black hose running from the tank to the passenger side frame rail up by the timing belt cover. that hose just dips into the frame rail..
> 
> remember, we are talking about an 84 vw here, not a 2004..
> 
> usually the only time a vehicle has a pressurized tank, is if the vent is clogged, and it went from cool to hot outside, then the fuel and air in the tank expand..


and the fuel goes through the lines that arnt connected and drip alllll over you're freshly painted engine bay:sly:


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## Rabbitissimo (Dec 21, 2009)

I have been reading CIS manuals for months and it stated in one of them the gas cap seal is another consideration, to "lightly pressurize" the fuel tank, something to do with atmospheric pressure. It even mentioned the oil dipstick seal, and they both sound crazy to me too, but there they were in the CIS FAQ area, in one of the manuals.
Just passing on what I have dug up.
I know one or two fuel pumps get the fuel to where it is needed, not like it relies on pressurizing to push fuel.
No idea why it would matter, except to keep water out.

Please help correct it if it is wrong.

Update~Just checked Cabby Info, they also confirm the oil dipstick theory. (Vacuum diagram area)
Too tired to check all the CIS manuals for the gas cap-It was in my notes from reading, though.
And if your gas cap seal is disintegrating, why not replace it anyway? A little chunk could fall into the tank, and who knows what chaos will unfold?
And, last I heard, water in your gas SUCKS!


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## WaterWheels (Aug 14, 2005)

*RUwagen* - Not a whole lot to work with but it would seem that either it is getting too much fuel or too little when the throttle is opened fast. Could also be an ignition issue, but I don't know the exact ignition system being used, but ignition is less likely. The best step to take, if you can, is to have someone test the exhaust gasses to determine the mixture. Once you know for sure what you have for a mixture setting, you can go from there, or just keep trying things in the hope you stumble upon the problem.

The fuel tank being sealed or not sealed is basically an emission issue. years ago it was OK to allow the vapor to escape into the air but now it is not. All the systems have a vent for the fuel tank, they have to. Newer models vent the tank into the charcoal canister to have the trapped fuel vapor sucked into the engine later. removing the cap is for a few reasons under different conditions. Releaving any possible pressure while opening the fuel delivery system so you don't spray fuel all over is one. Testing to see if the vent might be clogged is another (have seen old metal tanks become crushed a little from the vent being clogged). But in no case will the cap have to be removed to solve a false air situation.

The dip-stick is a different story on some engines. Some systems re-circulate the crankcase air or might be called a closed crankcase vent system. I can't recall any CIS system being this type, but Digifant systems should be. the vent hose for the crankcase leads into the intake air ducting after the air flow sensor. If air enters through a bad dip-stick funnel, it flows through the crankcase and into the intake air. that causes false air (un-measured) to enter the engine.


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## RUwagen (Mar 3, 2010)

*Update*

well heres an update...i realized after putting on a new fuel filter that the fuel pump start going crazy...and this is what i mean...the car starts and it sounds normal, car idles normal, then the fuel pump starts to get faster and faster till it gets all erratic in its buzzing, so obviously im not sure whats causing the erratic whirling of the fuel pump, but i know its whats causing the problem. once it speeds up and goes crazy, the car doesnt idle as smooth, it seems to be pushing too much fuel through the system. (the fuel pump is new also) so any ideas of what can cause the fuel pump to gradually get faster and faster then run erratic??  :banghead:


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## WaterWheels (Aug 14, 2005)

The fuel pump sounds like it is bad. I know, I read that you replaced the pump, but did you also replace the transferpump? An 84 is the first year I believe (without looking it up) that an in tank transfer pump was installed. If that pump goes bad and can not feed the main pump, the main pump starves and goes bad. Transfer pumps are rather cheap and just installing one might clear things up if no damage was already done to the main pump. Another option, cost more but if you plan to stay with CIS you really need one, is to purchase a fuel pressure test kit for CIS. With that you can troubbleshoot many CIS issues, like this one.


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## ds1919 (Oct 13, 2004)

no transfer pump in an 84 rabbit gti, just the solitary high pressure external pump, and the fuel line located at the bottom of the tank to it.

Remove your fuel filter and blow thru it in the opposite direction that fuel flows thru it, onto a piece of white paper. If its loaded with grime (from moisture sitting in the tank and rusting it out), then you will see a lot of black stuff coming out, which clogs the filter, and messes up the AFR....

Also, remove your injectors and see if you are getting a conical spray pattern, make sure to have them squirt into a jar to prevent a fire.


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