Stuttering, not idling and not behaving!

[DRobbo]

Hi!

Having a few issues with my 1990 GT2, it's seriously not behaving!

It will fire up straight away, and just about idle (a bit too low even though the idle adjustment is at the limit) and rev freely when in neutral. It can then be driven around for a few minutes (maybe longer if only light throttle is used) before the engine starts to cough and splutter. Holding the throttle down does not hold the revs as they drop off and the only way to avoid stalling is to pump the throttle. If you do let it stall however, holding the throttle down with the ignition off for a few seconds allows the car to restart and the loop will begin again.

Any thoughts? I'm very confused by this!

(I think this is the right section to post this, but of course it may have nothing to do with fueling )

[Risocco]

Hi bud! You still running the original carb, or has it had a Weber manual choke swap?

Alex

[DRobbo]

Still running the Pierburg 2e2 carb... So far I've replaced fuel filter, fuel pump, distributor cap, rotor arm and coil... And although it all seems a tiny amount better, it's still very rubbish!

[GT Matt]

Has your rubber carb base gasket split? Sounds like air is leaking into the cylinder without any fuel in it!

[DRobbo]

It had done, but I replaced that!

Also replaced fuel pump, fuel filter, HT leads, dizzy cap, rotor arm, coil... And the plugs are new...

Frustrating!

[Nate]

have you got a copy of the pierburg manual? if not, PM me your email address and i'll send it to ya

[LEEP]

rust in fuel tank check filler neck

[DRobbo]

have you got a copy of the pierburg manual? if not, PM me your email address and i'll send it to ya

Pmed... Thank you!

[DRobbo]

rust in fuel tank check filler neck

The fuel tank is clean as a whistle, so I'm guessing it's not that?

[hiltow]

If your fuel system is ok then I think the clue to the problem may be in the fact that the car seems ok when cold but plays up as the engine starts to get warm.

The Pierburg carb is quite a clever piece of kit as it self-adjusts the fuel mixture during I think at least two phases between starting up stone cold, through warming up to fully operational through adjustments it makes by routing vacuum to different components. The main items on the unit that drive these phases are the thermal timing valve (round 50p-sized black plastic cylinder on left side of carb with vac hoses attached), the electric switch and thermovalve, so may be worth checking these out.

I said the Pierburg is a clever piece of kit, but unfortunately this translates into complexity, expense and aggravation when it goes wrong!

[DRobbo]

If your fuel system is ok then I think the clue to the problem may be in the fact that the car seems ok when cold but plays up as the engine starts to get warm.

The Pierburg carb is quite a clever piece of kit as it self-adjusts the fuel mixture during I think at least two phases between starting up stone cold, through warming up to fully operational through adjustments it makes by routing vacuum to different components. The main items on the unit that drive these phases are the thermal timing valve (round 50p-sized black plastic cylinder on left side of carb with vac hoses attached), the electric switch and thermovalve, so may be worth checking these out.

I said the Pierburg is a clever piece of kit, but unfortunately this translates into complexity, expense and aggravation when it goes wrong!

Unfortunately it doesn't seem to make a difference if it's hot or cold, just depends on how I apply the throttle. E.g. I drove to work this morning keeping the revs as low as I could and there were no issues. However, if I were to apply full throttle it would begin by having restricted revs, before coughing and spluttering... This behaviour would then continue even if I was gentle on the throttle again...

You're right though I think the Pierburg (Pooburg??) is the next step... Just ordered a rebuild kit

[hiltow]

I truly sympathise with your predicament DRobbo and admire your bravery in taking on rebuilding the Pierburg yourself!

The problems with Pierburgs tend to come from the components forming the trickery that manage the autochoke and emissions control systems, not necessarily just the main block of the carb. The main issue is that (even after reading the Haynes manual) it's quite difficult to understand how these components operate together - they do and it only takes one of them to be faulty for running faults to happen.

Whilst not experiencing the same fault as you, I currently have a problem with my 2E2 carb fitted to my 1.6GT. Fuel and sparks are ok but the car just coughs and splutters on turnover. This began after the car gradually lost revs under idle over 5 seconds (see my earlier post from last summer).

My Pierburg operated 100% as intended before, which it should on a 25k mile car. The biggest challenge is finding an outfit who have the expertise to rebuild / repair one of these - given their reputation I found that there's a lot of hysteria out there about these carbs from specialists who don't want to bother with them given their complexity and reputation.

Given the good original condition of my car I didn't want to give in and go down the 'oh just bolt a Weber on' route as I felt it was worth the extra hassle and expense of getting the Pierburg fixed. My carb's currently being rebuilt to concours standard by Northampton Motorsport Ltd. who seem to be the only outfit in the country willing to work on a Pierburg.

Might be worth contacting them if get into difficulty. However, whilst my carb's not yet ready (and so can't vouch for their work yet), I was very impressed by there operation and with the knowledge and attitude of the guy there. Fingers crossed it'll be fine when I get it back - I'll update my original post when I do.

[DRobbo]

Oh dear...

This is now very embarassing...

Having replaced the carb mounting rubber THREE WEEKS AGO I've ONLY JUST noticed something... Where does this vacuum pipe go? OH CRAP!!!

However, it still lacks power and will not pull through the rev range, and sometimes won't idle... So still got work to do!

Thanks for all your pointers, I'm going to try and rebuild the carb i think.

PS Oh and I need a new CV boot too,

[Jay4424]

may have a cv boot for ya, but then they are faily inexpensive!

jsut before you do rebuild, go to a proper tuning garage and get them to check the fuel pressure coming out of the fuel pump, and then at the carb its self.

Fonzooroo had a huge fault a month back, i seem to remember a problem was lack of fuel, a restriction in hte return to the fuel tank, forcing more fuel to the carb, helped alot. He was running a weber and the end result weas that teh needle needed changing, but hte fuel starvation did improve things and certaintly wasn't helping.... may help you out


...he did post all on here.... somewhere!



cheers, Jay.