Slight hesitation under full throttle...+ other Q's (+pics)

[Dan_T25]

Hi all,

We've had our van (2ltr Aircooled 1982) for a couple of weeks and completed a good few trips under our belts, whilst pottering around I've noticed that on moments of full throttle (foot flat to the floor) on steep inclines that there this slight hesitation from the pull of the engine, a very stubble jerking motion.

The feeling is like its either over/under fuelling or suffering for air.

The van revs feel and under usually driving its fine and dandy. Within the last 18 months the previous owner had a lot of engine work done, new internals etc, which is all recorded and receipted.

The only other thing which I can think of is that the exhaust has a slight blow and the heat exchangers are in a poor state and need replacing (near side is actually disconnected from back). All on the agenda though over the autumn.

Can anyone give me some pointers to look for anything else?

Thank you,
Dan

[itchyfeet]

Lac of fuel supply perhaps caused by blocked filters
Up a hill on full throttle is max fuel flow you wil ever need

[Dan_T25]

Lac of fuel supply perhaps caused by blocked filters
Up a hill on full throttle is max fuel flow you wil ever need

Cheers I will check into this.

One thing I didn't mention above is that ours has an electric fuel pump plumbed in, on my list if to change the pipe work and filter and wiring which looking at it, looks like a bit of a bodge.

[itchyfeet]

Also check vac advance and retard if its fitted works on the dizzy

[Dan_T25]

Also check vac advance and retard if its fitted works on the dizzy

Thanks i'll check it out - planning on having a good rummage through this afternoon once back from a christening...

[Dan_T25]

Had a good route around...getting to know more about the engine and comparing it to the pictures in the Haynes manual....

I believe from investigation that the cause is down to the vacuum pipework which is missing i.e. no direct air feed to the air intake and the woeful fuel pipework/filter and electric fuel pump & brilliant wiring (to the coil that red core runs...fantastic!).



God knows what this is supposed to be....a replace pipe...hmmm. Spot the great zip tie bushing on the carb/throttle bar..







Anyone know what the correct pipe size should be between fuel tank - filter - pump - engine should be? I'd like to replace this as a matter of urgency.

The heat exchangers are not in the best shape either...the blown is out the near side exchanger when covering the tail pipe









They are physically not connected to the elbow parts...

I would really love to meet up with someone on Saturday at Busfest to get a "crash" course in T25 mechanics...or at least a nosey at a pukka one so I can compare and contrast? Shame we are late to the scene so couldn't get camping tickets...

On another note, the OP sensor isn't working...no light on the dash when ignition on. Can someone please point me in the right direction to where this is to replace/investigate the sensor?

Cheers,
Dan

[BOXY]

Starting with the engine bay.

The silver ducting should be connected to the air box inlet. At the mo' your engine is sucking in warm air from the engine bay instead of clean dense(r) air from the space under the grill on the side of the van.

On the rear bulkhead is something that wasn't there when the van left VW. I'm guessing that it's either a fuel pressure regulator or a filter? Any chance of a better picture?

Have you got vac tubes connected to both sides on the can on the dizzie? It looks like there is only one. Usually the vac tube is tee'd off the air box, but yours isn't.

[Dan_T25]

Starting with the engine bay.

The silver ducting should be connected to the air box inlet. At the mo' your engine is sucking in warm air from the engine bay instead of clean dense(r) air from the space under the grill on the side of the van.

On the rear bulkhead is something that wasn't there when the van left VW. I'm guessing that it's either a fuel pressure regulator or a filter? Any chance of a better picture?

Have you got vac tubes connected to both sides on the can on the dizzie? It looks like there is only one. Usually the vac tube is tee'd off the air box, but yours isn't.

Hi BOXY; I think its a fuel pressure regulator - here's a better(ish) pic:



(sorry taken with a ipad not particularly focusing on the back of the engine)

Other pic of the dizzy - I see what you mean on the can.

[itchyfeet]

Yes defo a vac pipe mising from the dizzy

[Dan_T25]

Yes defo a vac pipe mising from the dizzy

Cheers - where does this connect to or do I have a mis-mash of pipes due to the regulator?

[BOXY]

Here's someone else's engine showing the vac pipe tee'd off the air-box. Before you connect it up put a piece of pipe on the dizzie can and suck on it. If you can't suck against a dead stop the can might be u/s. If you can suck against a stop connect it up but you'll probably have to re-set the timing if it was set up without it connected.

[Dan_T25]

Thank you

[BOXY]

My turn for a question now. What the hell is that metal pipe that goes over the fuel hose, between the pump & the filter. It looks like it comes out through a hole in the floor?

[Dan_T25]

To be honest...I have no idea.

It is a reinforced rubber pipe which disappears upwards towards the drivers seat is (in orientation)...I want to strip all this bit off and install the fuel pump/filter and associated parts properly.

**E D I T...sorry on second thoughts I think this is a drain or ex water feed for the water/sink system. I will have to check. The water tank has been removed and the drain is surplus.

[BOXY]

That would make sense. Having it resting on the fuel hose isn't a good idea though. Is there a water tank underneath on the near side of the van?