'90 Golf faltering for a second. Transfer fuel pump?

Hi, Checking in with the gurus. I have a '90 Golf (gas engine, 8 valve) that's been exhibiting short bouts of faltering on acceleration most
times when going uphill. The engine doesn't cut out entirely and continues running, but power is severely reduced so the car essentially coasts for up to 1/2 second. Not too long, then the engine returns to normal power and the car continues to run fine again. The faltering won't appear again for weeks or months. But today, it was pretty bad and I moving onto the main road from an alley and was left exposed without any acceleration with oncoming traffic bearing down. After faltering for what felt like a full second, the engine came back to full power. I'm thinking the transfer fuel pump. I believe it's the original at almost 19 years old with 216,000 km on it. Is that a logical place to start? The main pump isn't buzzing so I didn't think it was starved for fuel. If it was the fuel pump relay or an electrical problem, I'm guessing the engine would just quit. Other than the infrequent faltering, the engine runs fine.
thanks.
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Did you notice any black smoke or smell any unburnt gas coming out of the exhaust?
With the Digifant FI systems I usually find that the ground wires near the rear of the cylinder head or intake manifold have broken. That causes a serious loss of power and gas mileage. Also I have repaired wiring to the Throttle Body also.
I have also replaced a few Fuel Pressure Regulators too that leaked fuel through the vacuum hose sporadically.
A clogged catalytic converter or muffler could also cause running problems.
Of course check your distributor cap to make sure that center tip is still there and I ONLY use BOSCH distributor rotors. I have seen more than one aftermarket rotor fail causing nasty running problems.
Just some ideas!
--
later,
(One out of many daves)
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Thanks Dave, The faltering is very intermittent, I can drive 1-2 months with nothing, then a 1/2 second faltering then good for another month or two. It usually happens when accelerating or under heavy load going up a hill. My gas consumption is normal, no change at about 6.2 L/100 km highway and about 11 L/100 km city (38 mpg and 21 mpg per US gallon or 46 mpg and 26 mpg Imperial gallons, respectively). Also I start the car in the garage and haven't noticed any smell of unburnt fuel.
I just checked if the transfer pump is running and it is when I turn on the ignition but that's not to say it doesn't stop once in a while. Will check for broken wires.
thanks, -Tony
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I had a similar problem with my '83 GTI ... twice. First time it was the ground strap between the engine and the chassis going bad ...when I accelerated, the engine twisting in the mounts was enough to break the ground connection. The second time it was a broken wire in the harness coming from the hall sensor in the distributor.
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Hi, Some more diagnosis and a possible fix. I checked the ground straps and checked for vacuum leaks. Nothing obvious. The distributor and cap are relatively, new, maybe 6 months and I only use Bosch parts, they looked good. I changed the transfer fuel pump (about 18-19 years old) but that didn't help, engine still faltered. In fact stalled right away after starting. Doing some reading, someone mentioned the fuel pump stops if the coil isn't sending out pulses on the high voltage terminal. The idea is if the engine stops running, say in an accident, the fuel pump doesn't keep pumping fuel into a potential fiery situation. The coil connectors were a bit corroded so I cleaned them and applied dielectric grease. Since cleaning the coil contacts, I've driven 1,200 km over the long weekend and there hasn't been one instance of faltering. The coil contacts may have been the problem. Will report back in a couple of months. Good mileage this trip too, 5.6 L/100 km or 42 mpg (US Gal) or 50.4 mpg (Imperial) on a gas engine, with a fairly full load with mountain passes topping out at 1,240 m and some 11% grades.
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Could you please point out where those connectors are situated at so I could search for any rust traces there? Thanks in advance!
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Hi, Our cars have gas engines and yours is diesel so you won't have an ignition coil. I haven't worked on diesel VWs so don't know the lay of the land. If the engine falters, it could be one or more of three things: air supply for combustion, fuel supply, or maybe a worn out ignition switch which causes the engine to think it's turned off. In the gas engine, the 4th element is fire which was our problem--no spark at the spark plugs for a brief moment.
What are your symptoms? Stalls? Or falters but eventually keeps running? Very predictable or very intermittent?
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missatge: snipped-for-privacy@m7g2000prd.googlegroups.com...

Thanks for writing back, Tony! :-)
The engine may falter many times in a row, but it keeps running and it's totally unpredictable. This issue may not show up for like a couple months then do it non-stop for a week. This has been happening on and off for over a hundred thousand miles now. The relay #109 is in like new condition--replaced once. I took the car to many car mechanics --both VW dealers and independent-- but they didn't seem to have a clue about this engine problem. Nothing seems to be recorded permanently on the on-board computer.
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Hi, I'm afraid I don't know what to suggest, I'm not at all familiar with diesels other than the theory on how they work. Somethings to check: - clogged fuel filter? - combustion air flow unbobstructed? - exhaust system not periodically clogged or broken? - any relationship to how full is the fuel tank? - wiggle the key in the ignition to see if problem goes away? (worn out contacts in ignition switch) - your fuel consumption/mileage reasonable? - any difference when engine under load or just cruising? - not sure if a diesel has vacuum lines, but if it did, any leak?
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Thanks Tony! I'll keep and eye on those things but this faltering issue is so sporadic that it'll take me some time to check them out.

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Congrats on your finding the problem and thanks for posting the solution! ;-)

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wrote:

Hi Dave, Thanks. But wait for the longer-term results to see if I really fixed it!!! cheers
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missatge: snipped-for-privacy@w37g2000prg.googlegroups.com...

I sort of have the same problem with my VW Golf, but mine is a 1995 Golf TDI 90HP.
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