Flushing Petrol Tank?

[Shotage]

Hi all.

Been having some issues with my 1988 1.9 petrol van.

After changing the fuel filter everything seems pretty good, but in time flat spots come and then it gets worse and will eventually splutter, backfire and conk out. Leave it a few minutes and it might be okay. The latest problem was not starting, it was turning over but not firing. Replaced the fuel filter again and starts first time and seems to run okay.

I know of the rusty petrol tank problem but I'm not sure if this is the problem here, at the moment anyway.

I recently noticed that the rubber elbow joint behind the petrol filler cap had completely perished and all sorts of dirt and crap would have been coming off the wheel in going in there. So I'm hoping that this is the problem but wondering how to fix it!

I have once already drained the tank, but should I flush it with something? I don't know if there is a product to do this?

Also, I have also heard of a common problem of fuel filters being too small, meaning the fuel pump sometimes struggles to pull through enough.

So I'm thinking if I can flush the petrol tank and add a larger fuel filter maybe this will cure the problem.

Love to hear your thoughts and advice please, if you have time.

Finally, if I have to go the route of dropping the tank to take a look, is it possible to do on axle stands? I don't have access to a pit or such like.

Thanks,
Andy

[marlinowner]

I can answer you question about dropping the tank, I changed mine on my own with the van on axle stands and a trolley jack under the tank.The pipework on top of the tank is a bit of a pain though. Once I'd got the tank off and looked at it I decided to just fit a new one as mine was pretty corroded on the top.
There will be a lot of water getting in to your tank if the filler neck is gone, that will lead to misfiring etc. I would say get the filler neck sorted out, drain about a pint out of the tank and see if there is any water ie two separate layers in a glass jar. If not see now it runs, if it plays up then check there is a good flow of fuel if you disconnect at the filter.

[CovKid]

Could also be pump not keeping up with demand, some or part of the time. I was plagued with these symptoms over many months and its not easy to diagnose. However, if there are routes into the tank for muck and debris, best to sort that first. I went all electric on the pump and all the issues I had promptly vanished.

[Alzey]

WHS and for my tuppence worth yes you can do it as I have done it today, (new SS water pipes fouling the gear selector rod but thats another saga) ) it is a bit of a pain to do. Get the van on axles stands give yourself as much space underneath as poss. Remove both fuel pipes to carb and return, drain tank. You need to pull off the breather pipes (x4) that are tucked up in the wheel arches (both sides) undo the 13 ml bolts that hold the restraining straps in place and having put a trolley jack and with some wood between the jack jaws and tank to spread the load and save denting the tank lower it gently about 12" you can then get your hand in and gently pull off cable to fuel sender and then pull off the breather that goes acoss the back of the tank. Gently lower the tank to the ground. Forget to mention you will need to pull out the filler pipe to the tank,it just sits in a very large grommet. Then have fun trying to get the rest of the fuel out because as much as I swilled turned it over etc I couldn't get the last dregs out. TBH if you can get another pair off hands all the above will be a bit easier as the tank is unwieldy and fairly heavy. Whilst you have the tank out you can you can lay on your back and look at the state of the handbrake, brake pipes and everything else that runs over the tank....it all gets a bit daunting.
Surprisingly the top of my tank wasn't to bad and will need a bit of krust treatment in one corner. I haven't taken any photo's but it is out at the mo in bits and can do if you need any help. The filler pipe elbow bits you can get from brickwerks I got mine from vw heritage and it doesn't come with the three screws, the brickwerks one does. I spent a couple of hours fannying about trying to get three screws to fit so if you have to replace it... well up to you. BTW I also replaced my fuel pump rod it was cattled hence sufficient fuel wasn't getting to the carb.

Good luck Al

Al

[Shotage]

Thank you so much.

Yes I have now fixed the rubber elbow joint, I then ran the van nearly out of petrol (or so I thought!) and then drained the tank completely. I could see some black grit and dirt in that petrol.

This fixed the problem for a while, drove like an absolute dream but them the issues came back, first just flat spots, then more often and then not starting.

Just changed the fuel filter again and seems to be running pretty well. But I suspect that it's only a short term fix and I think I need to have a proper look at that tank. Maybe!? Ha ha.

CovKid, when you said you went all electric, do you mean you replaced the mechanical pump for an electronic one? If so, I'm curious to know how you went about this. Is it a case of just replacing it with an electronic one?

Thanks again.
Andy

[Shotage]

Al, thanks so so much for your reply. That really is very useful.

Andy

[CovKid]

Electric pump goes next to your fuel filter underneath Andy. The fact you can't start (and I'm not saying its not tank crud) could be due to the line going dry. Mines a daily driver and I was getting a start but it would conk out about a minute later as it had used what was left in carb but with zilch in the line, it died. I'd also get unpredictable running and acceleration when on the road. Sometimes I'd arrive at a junction, it'd die, then not start. If you're not a daily driver then it might not start at all, or barely.

Search for 'Facet' on here. They're relatively cheap and very simple little pumps with little to go wrong. You can also fit a switch and prime the entire line before starting if you wanted to. You'll need to replace fuel line but other than that, its not hard to fit. Mech pump stays where it is with no line connected - as a sort of blanking plate. You can take out the pushrod if you want to give it early retirement.

The symptoms are not uncommon for a weak or dying pump and you just have to weigh up whether the pump should be mech or electric. I'm not entirely convinced that replacement mech pump diaphrams tolerate modern fuels to be honest. I can give mine some welly now in confidence, rather than as before, constant trepidation.

Changing the filter might seem to clear the problem but that may not be the cause and even with a slightly blocked tank, an electric pump will still deliver. Thats why you need a good fuel line - the extra pressure will find any small leaks between pump and carb.