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Engine idling and running issues

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Hi, I'm slowly working through the 76 5 door (see thread in projects page) but can't get it to run right.Its a 1600 FN engine with 34 PICT-5 carb and mechanical fuel pump.

When we first bought it, the PO pointed out he couldn't get it to run lower than 2k revs, so I obviously looked straight at the idle circuit. A missing (yes missing!) idle jet was the problem so after a full carb strip down and clean, I had it idling great. Next sorted out the overheating issue by replacing the stat, fan switch, water pump and flushing the system.

So now we are test drive phase but seem to be taking steps backwards. Before fully sorting the overheating, we did take it round the block and it seemed to run ok - not brilliant but ok. Though since then its gone south. First it developed a leak from the fuel pump so replaced that and in the couple of test drives since then it is all over the place.
Not idling anymore, cuts out regularly and is lumpy as well. Seems to not be running on the idle circuit again. Given that the only thing I changed was fitting an after market fuel pump I wanted to figure out if that was the cause.

I've took the carb top off and sure enough, no fuel. So looks like I had nailed it but to check the pipework, I disconnected from the carb and turned over the engine - fuel pumping through! So refitted carb top and pipe and turned the car over again - float chamber filled up so the stop valve seems to be working ok.

Has anyone seen this before? Why would the float chamber be empty when trying to drive but is filling up ok when turning the engine over? Has anyone had a pump that was strong enough to fill the chamber but not strong enough to keep up with the car when driving?

Or am I being blinded by assuming its the pump - could it be something else?

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It could be something else, like a blockage in the tank that comes and goes. Had that before with big bits of rust blocking the filter in the pump, reducing the flow and causing a lack of petrol at the carb.

However, I've also had problems with mechanical fuel pumps. Some with too much pressure and others without enough pressure. Too much and fuel is pushed passed the seals and the engine 'runs away' and too little pressure and it's fine on tick over but as soon as you try to run it under load all sorts of mis fires and hesitation.

If you have an electric pump knocking about it might be worth trying that instead? Or indeed trying another fuel pump from another manufacturer. I went through 3 for my small block until I found one that worked properly  :'(

Good Luck

Ian

Cornish Host.
1980 VW Derby
Clive the Cabby
Ujum the Invisible
Mynx the  Tintop

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try gravity feeding the carburettor if the carburettor fills
up the float chamber then surely you work from front to back is that  not an easy solution

Do not know a lot but willing to help if possible

1989 Sapphire Blue Mk1 Cabriolet KR
1985 Atlas Grey Mk2 GTI 2.0 ABF

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The idle shut off valve might jam shut occasionally due to a bad ground or being defective. It should click every time when 12v is applied to it. If the ground cable to the Solex is disconnected it might not work properly.

Early 77 year model Golf. 4-Door

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Thanks all, some things to think about there.

There are a couple of NOS Brosal pumps on TheSamba so I'm finding out shipping costs. I figure Brosal is better than new aftermarket.

I'll also check out the idle shut off valve - the car has a lot of bad earths I think due to the amount of time its been off the road and overspray from the home done respray.

Not sure about a blocked fuel line. The fuel is coming out a bit mirky so does suggest there is some rust or crud in the tank though the PO said he's cleaned it out.  There's no indication of a blockage such as distortion of the fuel filter and that also seemed to always have fuel in it. So I might give the tank and lines a flush out but don't think it is being caused by a blockage.

Thanks
Keith

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Cutting out after running OK for a while and/or not restarting until left for a while are text book symptoms of road debris and rust in the fuel tank and fuel lines from a rotten filler pipe. Remove the inspection cover and level sender under the rear seat and shine a torch in to see if its full of cr P   

1983 Mars Red 1.8 Golf GTI
1987 Alpine White 1.8 Clipper Cabriolet

The trouble with doing nothing is that you never know when you are finished.

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Thanks, will check out the inspection plate 👍

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DO not attempt to remove the inspection plate and sender if you have over 3/4 of a tank.  You WILL SPILL FUEL into your car…Creating a FIre HAZARD……

IF you are unsure as to the Quantity of Fuel, Please Drain or Siphon it out…… for a 10 Gallon tank tank a couple of gallons out.  For a 13 Gallon tank Take 4-6 out.



What do Divorces, Great Coffee, and Car Electrics all have in common?

They all start with GOOD Grounds.

Where are my DIY Links?

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Don't panic I've played with enough fuel tanks over the years and not managed to burn one yet.  :thumbs:


I can't understate how rust free this car is and the fuel filler pipe is in great condition. Thats the benefits of a car thats spent most of its life in Canberra and country Victoria…….Now its in Queensland it'll probably crumble to dust in no time!!  :o

Anyway, emptied the tank and peered in. Looked ok - sure there's a bit of debris at the bottom but certainly not too bad…………or so I thought.
I disconnected the lines to blow them through and the filter (which I'd only fitted a few weeks ago so literally only about 40 minutes of engine running) was blocked solid.
So have decided to drop the tank and clean it properly. I've read Borednow's write up (thanks) so will order new bushes and brake lines before dropping the rear sub assembly.

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Don't forget to replace the filter.

What do Divorces, Great Coffee, and Car Electrics all have in common?

They all start with GOOD Grounds.

Where are my DIY Links?

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Don't forget to replace the filter.

It might leak slightly as I cut it up to see how blocked it was! 😉

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