Loss of power at high revs and stalling when stopping
Posted: 23 Jul 2010, 13:12
Hello all,
Now the above two problems may or may not be connected but as the van isn't going anywhere at the moment it would be good to get it mobile again at least. First a bit of background...
1990 1.9 litre water cooled boxer (DG maybe - I haven't got the details to hand)
Following a failure to run over the winter (mechanic cleaned out the carb but that didn't fix it) the Pierberg carb was replaced with a Weber carb from jk. In terms of tuning it was very much twiddle the knob until it idles OK. The van ran fine (if a bit rich and with a thirst for petrol) for several months until recently when it was backfiring in a quite fantastic manner due to an exhaust problem. The exhaust was fixed at Manchester Air Cooled who also gave the carb a quick twiddle to try and stop it running as richly a few weeks ago.
About a week or so ago the engine would stall when coming to a stop, at first intermittently for a short period after then engine had been started warm. This has since become more regular happening at the most inopportune moments (e.g. trying to get across a busy A-road last Friday in the Lakes).
On Sunday on the return journey the van started to lose power at high revs (after 20 miles or so on narrow country roads and then fast A-road where it was fine) ending up in a layby and a call to the AA. The weather was really very, very wet during this. There wasn't wany water visible on the electrics but I tried giving them a good spray with WD40 anyway to see if water ingress was affecting the electrics. Then van got as far as the next layby (fortunately not too far up the road) as there was still little power.
After a couple of hours the AA finally came and the rain had stopped. The engine ran fine in the layby but once on the road it suffered the same loss of power. It would make it up to 60MPH or so then the engine would die away; I'd release the throttle and it would seem to come back but not really, so I'd change down. Repeat until in first gear on the hard shoulder of the M6.
The engine suffered from the same loss of power when tried again on Wednesday after the weather had been reasonably dry (so it looks like it wasn't the damp affecting the electrics).
Anyway I have the weekend booked to try and see if I can get it running reasonably again so have been looking through the forums to try and get some tips...
* Check all of the cables (anyway even though it probably isn't the damp)
* Check the plugs to see if there are white deposits (indicating weak mixture) (plugs were changed a few weeks ago)
* Change the fuel filter (no idea when it was last done and it could be fuel starvation)
Those are the relatively easy things to do, then it seems I may need to get stuck into...
* Fuel pump - is it pumping properly?
* Distributor - err, need to read up on this a bit more and people talked about testing the vacuum to it
* Carb - has it got crap in it?
So finally my question is - am I on the right track with trying the above? Are there other things you would look at too?
Many thanks for any advice, the other project is de-rusting the bodywork for which I'll add my experiences to the wiki,
Gavin
Now the above two problems may or may not be connected but as the van isn't going anywhere at the moment it would be good to get it mobile again at least. First a bit of background...
1990 1.9 litre water cooled boxer (DG maybe - I haven't got the details to hand)
Following a failure to run over the winter (mechanic cleaned out the carb but that didn't fix it) the Pierberg carb was replaced with a Weber carb from jk. In terms of tuning it was very much twiddle the knob until it idles OK. The van ran fine (if a bit rich and with a thirst for petrol) for several months until recently when it was backfiring in a quite fantastic manner due to an exhaust problem. The exhaust was fixed at Manchester Air Cooled who also gave the carb a quick twiddle to try and stop it running as richly a few weeks ago.
About a week or so ago the engine would stall when coming to a stop, at first intermittently for a short period after then engine had been started warm. This has since become more regular happening at the most inopportune moments (e.g. trying to get across a busy A-road last Friday in the Lakes).
On Sunday on the return journey the van started to lose power at high revs (after 20 miles or so on narrow country roads and then fast A-road where it was fine) ending up in a layby and a call to the AA. The weather was really very, very wet during this. There wasn't wany water visible on the electrics but I tried giving them a good spray with WD40 anyway to see if water ingress was affecting the electrics. Then van got as far as the next layby (fortunately not too far up the road) as there was still little power.
After a couple of hours the AA finally came and the rain had stopped. The engine ran fine in the layby but once on the road it suffered the same loss of power. It would make it up to 60MPH or so then the engine would die away; I'd release the throttle and it would seem to come back but not really, so I'd change down. Repeat until in first gear on the hard shoulder of the M6.
The engine suffered from the same loss of power when tried again on Wednesday after the weather had been reasonably dry (so it looks like it wasn't the damp affecting the electrics).
Anyway I have the weekend booked to try and see if I can get it running reasonably again so have been looking through the forums to try and get some tips...
* Check all of the cables (anyway even though it probably isn't the damp)
* Check the plugs to see if there are white deposits (indicating weak mixture) (plugs were changed a few weeks ago)
* Change the fuel filter (no idea when it was last done and it could be fuel starvation)
Those are the relatively easy things to do, then it seems I may need to get stuck into...
* Fuel pump - is it pumping properly?
* Distributor - err, need to read up on this a bit more and people talked about testing the vacuum to it
* Carb - has it got crap in it?
So finally my question is - am I on the right track with trying the above? Are there other things you would look at too?
Many thanks for any advice, the other project is de-rusting the bodywork for which I'll add my experiences to the wiki,
Gavin