backfire, not electrical

[Hevsta]

Hi folks,

I've got issues with our 1990 crew cab, (engine air-cooled petrol, size unsure)

It's backfiring and losing power, but the prob only seems to be there when I'm up to speed- say 30-40 mph+

We've been told it's not electrical, but they're not sure what it could be... has anyone got any ideas what it may be?

For those who don't know me (I'm new and haven't been on here much) the dubster is my work vehicle (though obviously i have an emotional connection, it's hard not to) and I don't want the vehicle to retire or to lose too much work. I've been told that they'll pay for repairs, and they'll buy the parts asap if they know what it is.

I hope someone can help!! I've been told also they're looking to see if it's a leak in the carb, other than that we're stumped.

[72BUG]

Firstly are you sure it's Aircooled? They stopped putting them in vans in 1982, so it's strange to have one in a 1990 van.

[big red bus]

air leak on induction or on exhaust?
is the exhaust all in good condition and not blowing.
Can you hear any air leaks with it running around carb or manifold?

[Mushr00m]

Sounds like the vacuum hose(A very thin plastic or rubber tube) to the carb is either leaking or has become disconnected to me.

It could be many things but the vacuum hose is the easiest to sort judging from your symptoms.

Hope this helps.

[R0B]

As martin says.I very much doubt you have a 1990 Aircooled.

[sarran1955]

Hello,

Count the grilles on the front

Cordialement,

[Hevsta]

Hi, I doubt very much it's Aircooled too. My sister does have one, and I was in a bit of a frantic state when I posted- if the van is off the road, I'm not working (i'm also a single parent and it's the holidays)!

Thanks for your suggestions- the regular mechanics have scratched their heads, passed it over to electrical specialists who also scratched their heads- I went down after reading some of your suggestions and poked around and found a couple of damaged pipes.

I've managed to get one of the local VW wiz guys to look at it on friday, thanks to my sister.. But I've been able to pass on what I've seen that's relevant (thanks to your suggestions), and he thinks he knows what it is and is fairly confident he can sort it quickly.

Thankyou to everyone, I love my van and I hate to see it poorly!

ps some may think it strange that I don't know that much about the mechanical spec of the van- the local council arts team own the van, the council vehicle maintenance crew have to do the majority of official repairs- I own all the equipment on it, and I'm responsible for the upkeep of that side of things- I do the majority of wiring and repairs to the PA system etc. I run sessions with groups and attend events, which the arts team take the bookings for. They largely leave me and the vehicle alone most of the time, I have the main set of keys and I'm one of the main contacts for the vehicle, I do a lot of running repairs and suggest things that the council could do to improve it, but I'm the main person who drives it every day!

(phew, complicated... on the flip side, I'm planning on getting a T25 when i get the money together, my sister has a 79 bay (one of the very last with sliding doors on both sides) but I much prefer the T25!)

[Hevsta]

Just to let everyone know, the fault turned out to be a spring in the distributor... (forgive me if it's the cap, I was so happy all i heard was distributor!)

We've gone for a couple of years replacing rotor arm, distributor cap and coil etc, with the fault recurring on a regular basis... aparently this is the reason those parts kept failing!!!

I'd like to say a massive thanks to Jay, the most amazing mechanic on the planet!