poss vapor lock

[djhammy]

HI folks have had an ongoing fuel problem with the van cutting out when driving off but only when the engine is hot. Oh and my van is a water cooled late 1985 DG 1.9ltr with carb.

From cold i can drive miles and miles no problem. Only happens if i then stop to say go shopping then drive off say 10-20 minutes later. Give it an hour or so usually no problem. never get the problem if i drive off in the morning or having left the van for a long period of time.

Have replaced fuel hose, though couldn't see any split or leak, have replaced with a new Brickwerks pump, and done numerous checks as per recommendations.

Happened to me 3 times last night. was dropping flyers off to various venues. Every time i drove off the engine cut out a short while later. I then have to whip the fuel hose of the pump and put a hand primer on and pump the fuel back up and of it goes again but this happened 3 times last night.

The engine does seem to be very warm and i have just started getting odd noises from what i think is the water pump but replaced the old fan belt as a matter of course. seems to be going ok but still the odd squeak and a constant shimmering sound.

The temperature gauge never moves much above the bottom end so have assumed all is ok but wonder if that is faulty and the engine is getting warm and as the fuel hose sits above the warm engine is the fuel possibly vaporising and causing my problem. I have tried everything else so wondered what your thoughts are.

Oh and where is the temperature sender situated so i can check it.

Driving me nuts for sure.

Some intersting stuff in the wikki link. especially this thread
http://en.wikipedia.org/wiki/Vapor_lock" onclick="window.open(this.href);return false;

A vapor lock is more likely to develop when the vehicle is in traffic because the under-hood temperature tends to rise. A vapor lock can also develop when the engine is stopped while hot and the vehicle is parked for a short period. The fuel in the line near the engine does not move and can thus heat up sufficiently to form a vapor lock. The problem is more likely in hot weather or high altitude in either case

[BOXY]

Does the carb feel hot? The gasket between the carb and the manifold should reduce the transfer of heat by conduction. Maybe the gasket has been replaced by one made of the wrong material? My old Fiat X19 had a fan for the carb to stop the petrol evaporating. As soon as the engine was switched off the fan would kick in and run for a few minutes to cool the carb (or flatten the battery if the fan stuck on)

[Ian Hulley]

Check the carb heater is switching off, it's the red sensor from the nearside of the thermostat housing on late cooling system (the one used for the injection systems on the 2.1i ) the guage one is stuck in the side facing the front of the van.

Ian

[kevtherev]

I don't think it's vapour lock.
There should be enough fuel in the float bowl to start the engine and pull fuel through from the tank even if the lines are empty.
This might sound like a faff but the next time it won't start... find out if it is actually a dry carb?
Was the pump checked or compared to the old one?


Because the fuel is returning to the tank there are two reasons. which I'm sure you know. (air leaking into the fuel hose from a joint or split near the pump and a split diaphragm)
Since you have replaced the the obvious I would now try to cure it another way, and fit a non return valve in the hose next to the pump



temp sender for the gauge is on the thermostat housing (yellow/red wire)

[djhammy]

HI kev yes you are correct there is always enough fuel to start the engine and it always does start. It simply cuts out say after driving off after 10-20 yards. And only when the engine is hot. If i leave it a fair while i don't have this problem.

Surely if i has a split hose i would get this from cold not just when driving off again shortly after stopping.

Re pump the old one i replaced was only a year old itself. i replaced it with the brickewers built like a tank one as just a precaution and method of elimination. Makes no difference if i put the old one goes back on.

So i really don't think its the pump. Pumps fine whilst driving along.

I will fit the valve now. I was told i should do this near the tank rather than just before the pump?

Cheers Dave

[kevtherev]

makes no odds
With it near the pump you can see if any air is in the pipe easier that's all

It simply cuts out say after driving off after 10-20 yards. And only when the engine is hot. If i leave it a fair while i don't have this problem.

so, after it cuts out.. if you leave it, let the engine cool and you don't prime the line it starts OK?

[djhammy]

Cheers kev haven't fitted one yet will purchase tomorrow though unsure where.

Did fit a clear fuel filter in-line at the engine bay end to see what's happening and once i stop you can see air bubbles coming up and the fuel going backwards.

The only hose that hasn't been replaced is the hard plastic one. Maybe thats needs to go.

Carb and engine bay is very warm to say the least. No leakage of coolant but wondering if its getting pumped round ok?

[colinthefox]

Now it's a long time since I had a p***ol vehicle, but as it happens, following a tuning tweak or two this summer, my p***ol mower had ben vapour locking when it was hot and I stopped to unload. I tried all sorts including diverting cooling air over the carb, changing fuel filter, stripping/cleaning carb, but all for nowt. Then I checked the float level and it was 3mm low. Correcting this cured the problem.

Mental note to self........Must get a proper oil burning mower.

[poodlefaker]

Hi Dave,

Its not much help to you, but I am getting exactly the same problem and always seems to stall at a T junction or car park entrance 20-30 yards from where I started I have now fitted a non-return valve http://www.thornycroftparts.co.uk/Non_R ... 22910.aspxjust before the fuel pump and it happened again, so I`m following this thread with interest.

Julian

[djhammy]

HI Julian I was about to buy one yesterday when a friend rang and said a fuel filter is a non return valve so i fitted an one just before the pump. Didn't make a jot of difference.

I have become an expert of swerving into lay byes and avoiding traffic lights.

I can see the air just bubbling up the line towards the carb. Mine doesn't cut out from cold if left overnight only when i stop and then drive off later any time from 5 minutes to several hours or more.

My only other area to attack is the hard plastic hose and the return hose though not sure if that would cause this.

Was going to Brighton this weekend but had to cancel. gutted.

Dave

[poodlefaker]

Hi Dave,

Likewise I am getting good at picking stopping points where I have a clear run for 5 mins after starting again. This seems to give enough time for the pump to get fuel up to the carb but if there is a junction or roundabout within 100 metres then I may as well put my hazards on .

I like the sound of the hand pump as I`m getting sick of the taste of petrol as the only way to get going again is to suck fuel up the line to the carb.

I`ve been under the van today and inspected the hard platic line all the way from the tank up to the engine bay bulkhead, also re routed the fuel hose in the engine bay to make sure it doesn`t touch any of the coolant hoses which might be heating up the fuel.

I`m running out of ideas now

Hopefully one of us can come up with a solution.

Cheers Julian

[djhammy]

HI Julian the hand primer i purchsed from Screwfix

http://www.screwfix.com/p/laser-diesel- ... tid=678979" onclick="window.open(this.href);return false;

I did actually leave it in line but the petrol made it go hard i found but left it in the sun today and its ok again

I have a clear filter between the carb and pump so i can see it coming up.


Cheers Dave

[djhammy]

HI Julian I see your only in Ringwood I'm in Southampton happy to meet up maybe to try resolve this.

Only 25 mins away normally lol

[poodlefaker]

Hi Dave,

Well two scratched foreheads could be better than one Have you managed to re-create the fault on your drive. I have taken the van out for a spin, got everything running hot and then parked it on my drive, switched off, come back after 20 mins, started fine as normal and then waited for the stall after a couple of minutes but it just seems to run fine ????? I really wanted to see where the fuel was getting to or not. It really only seems to stall in the most inappropriate places and then my main concern is getting out of there rather than figuring out what is happening. A couple of metres of clear hose would be interesting, I`m usually better when I can see whats happening.

Cheers Julian

[djhammy]

HI Julian i haven't recreated at home but yesterday morning i drove off then parked up. Restarted van 20 minutes later and we sat there and waited and the engine cut out after about 5 minutes. It did on this occasion start again and i gave it some revs and carried on running.

Running as rough as box of spanners though.

MY engine bay is very hot and i also need to run hose away for direct sources. i think the water pump is playing up I've just changed my fan belt but still getting a horrible squeak on start up hopefully just the belt slipping but it's been adjusted since fitting to take account of initial stretching.

Did you find any signs of cracks in the hard plastic hose? I think you can still get this hose but wondering if i can just replace it all with one continuous length of top notch rubber hose.

Clear hose is a good idea