metro
Part of things
Posts: 140
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Hi there, I wonder if any of you could help me out. A close friend of mine owns a 1990 VW T25 Holdsworth (see below). The engine is pretty standard - it's covered around 18,000 miles in the last three years, mostly trips in and around Europe. It's a 5-speed 1915cc watercooled 79 hp carburetor model. The problem starts when you are in 4th and 5th gear at 50-60 mph. While cruising along, within a couple of minutes it feels like someone has dropped an anchor out the window, juddering and engine-braking. This leaves two choices: down-gear and ease-off the accelerator, or pump the accelerator furiously until it back-fires and inevitably grinds to a halt. Initialy we thought it was a blocked carb, but after taking it apart and cleaning it out the engine wouldn't start, which lead us to believe it was the fuel pump, or at least a blockage in the fuel line. Since then we've replaced the fuel pump, part of the fuel line to fit the larger nozzle, new dizzy-cap and rotor arm, fuel and air filters and new spark plugs. And still the problem remains.... Any help would be very much appreciated, here are some pics for your troubles...  Beatrix3 by Wrytch, on Flickr  Beatrix2 by Wrytch, on Flickr  Beatrix1 by Wrytch, on Flickr  Beatrix by Wrytch, on Flickr |
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Last Edit: Nov 5, 2011 1:54:19 GMT by metro
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Did you clean the jets in the carb??? sounds familiar to a fault i had on a carb'd car
Also check for collapsed hoses and blocked exhaust.
I cant think of anything else right now
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would this have an AFM?  |
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mrj
Posted a lot
Posts: 1,662
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did you check the ignition leads, especially the plugs on them ? Check if there is a vacuum leak, too ...
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- 1971 VW 1600 TL Fastback
- 1978 Passat GLS Variant
- 1980 Audi 100 5E
- 1981 VW aircooled panel van (sold)
- 1983 VW Jetta Mk.I
- 1984 VW Polo Coupé
- 1984 VW Passat hatchback
- 1987 VW Passat Variant
- 1987 VW Passat hatchback
- 1988 VW T25
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dungbug
Posted a lot
'Ooligan!
Posts: 2,852
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I was going to say check for a vacuum leak too, I'm guessing the points have also been changed (?) When were the tappets last checked (too often neglected on VW's)
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Past: 13 VW Beetles from 1967 - 1974
Bay Window Campers (1973 & 1974)
Mini's (1992 Cooper lookalike & 1984 '25 Anniversary)
MK2 Polo Coupe S (1984 & 1986)
MK2 Polo Breadvan (1981 & 1984)
MK4 Escort (1989)
MK2 Granada Based Hearse (seriously)
Fiat Uno 60S (1986) Punto 60S (1998) Cinq (1997)
1998 Yamaha YZF600R Thundercat
2003 Ford KA
Current: 2004 Ford Focus (barely alive)
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I can't help sorry, but I recognise your bus, lovely looking thing, see it everytime I come to chaversham, I have a ratty satin black t25 diesel. Hope you get yours going soon
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Ads 19
Posted a lot
My old r19
Posts: 1,351
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i used to have a similar problem on my old t25 dj engined one, i tried all of the above. turned out to be a slight hg leak resulting in slightly bad running under load. probably will show on the plugs if its this or a compression test. would be suprised given the mileage. mine had done over 200k. still gave me an excuse to rip engine down. the skim and light porting livened it up a treat.
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Might want to check the fuel tank breathers as if the air can't get in fast enough to replace the fuel that is being pumped out, the pump will stop pumping.
Nick
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1967 Triumph Vitesse convertible (old friend)
1996 Audi A6 2.5 TDI Avant (still durability testing)
1972 GT6 Mk3 (Restored after loong rest & getting the hang of being a car again)
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Might want to check the fuel tank breathers as if the air can't get in fast enough to replace the fuel that is being pumped out, the pump will stop pumping. Nick I was going to suggest this too, try driving it with the cap off to check. |
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luckygti
Posted a lot
I need to try harder!
Posts: 4,912
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I had a similar problem with my old one, it was water getting into the fuel. I replaced everything and there was still water getting in somewhere! Drop the fuel filter and see what comes out. The fuel pump part that drops down into the engine was also snapped, never was sure if this was the problem, but I changed it anyway! As soon as I sold the bus the new owner never had a single problem with it  |
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When were the tappets last checked (too often neglected on VW's) i was gonna ask this. i had problems with my T25 aircooler similar to what your describing. turned out the hydraulic tappets weren't set correctly. might not be your problem but maybe worth a look.  |
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bortaf
Posted a lot
Posts: 4,549
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Obv check would be too pull the fuel pipe off the carb and check for flow, no flow it's a fuel problem  either blocked breather, wronge or blocked fuel cap or blocked pickuip pipe. If you have a flow look past the pump, carb float level, internal filter ect. If they check out does the carb have an anti runon/dieseling solenoid valve? then i'd move on to ign or possable air leaks but I doubt they would only show up at high load low revs they usually cause an uneven idle for starters, it could at a push be tight valve clearances that close right up when the engine is hot but I cant see it being that if it's only at high load low revs (IE 4th and 5th gear) again tight tappets usualluy show as a miss at idle tha tgets worse the hotter it gets ? Leccy ign? could be the modual overheating the more load on an engine the stronger the spark has to be to jump the gap in the plug so a weak spark may be the problem so is the coil getting hot when the problem happens. |
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Last Edit: Nov 5, 2011 14:56:13 GMT by bortaf
R.I.P photobucket
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It's not wind related is it? A friend of mine once had an motorcycle that would cut out at a certain speed (luckily for him above 100mph), turned out a part of it's injection harnass was shorting out against the frame!
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metro
Part of things
Posts: 140
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Hi its the owner here, thanks for great response :-D LOL no its not wind related, this beast Ive got up to 95!
With regards your posts I think the best thing for me is to get the heads skimmed and gaskets replaced anyway as they're beginning to leak and replace the exhaust manifold whilst I'm at it. I'll replace the whole fuel line and check for blocked breather in the tank. I wouldnt have thought there was rust in the fuel tank as the in-line filter I replaced is still clean a month on. I wont rule out tappets just yet as they're getting a bit noisy now. Being electronic ig. I would expect an issue running idle not just up to speed, the HT leads arnt that old but I could replace them anyway...
It does show more, regarding carrying load you notice it more when going up hill, obviously you have to open the throttle more so she really doesnt last long then!
In all honesty, seeing as I'm going to get the heads done anyway if anyone can recommend a good garage in Kent please let me know! I'll do the lines, leads and breather checks myself mind :-)
And thanks andyboy, I'll keep an eye out for you!!
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dungbug
Posted a lot
'Ooligan!
Posts: 2,852
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Might be someone on Volkszone that could recommend a local workshop to you, not my part of the world so can't help in that respect, sorry dude. Do check the tappets regularly though, used to check mine every 3k or so on the bug.....It does make a big difference when they're wrong, hope you get it sorted. |
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Past: 13 VW Beetles from 1967 - 1974
Bay Window Campers (1973 & 1974)
Mini's (1992 Cooper lookalike & 1984 '25 Anniversary)
MK2 Polo Coupe S (1984 & 1986)
MK2 Polo Breadvan (1981 & 1984)
MK4 Escort (1989)
MK2 Granada Based Hearse (seriously)
Fiat Uno 60S (1986) Punto 60S (1998) Cinq (1997)
1998 Yamaha YZF600R Thundercat
2003 Ford KA
Current: 2004 Ford Focus (barely alive)
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Could your fuel pump push rod be worn?
As you changing up to 5th at 60 you are dropping RPM's so the volume of fuel pushed through by the pump is lower but the engine is under the same load.
Just a thought as my 1700cc carb engine in my bay window had a similar problem and as the pump push rods are unobtanium I switched to an electric pump.
Dave
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either blocked breather, wronge or blocked fuel cap or blocked pickuip pipe.
