From: Gary Henderson
Date: Thu, 25 Mar 1999 10:00:42 +1200
Subject: [imps] Fuel system
One fuel-system weakness not mentioned in various threads is the tank outlet, which features a sudden constriction at the bottom of a hole (where the pipe-union goes on to a short but skinny neck). This is ideal for accumulating a certain size of petrol-borne rubbish, leading to mild fuel starvation (which can in turn cause baffling results to would-be tuners.) If a bronze-gauze 'bulb' could be found or made, of a size to push-fit into the neck, this problem would simply go away.
A good road-side fix (and also as routine maintenance!) is to push a bit of PVC aquarium tubing into the rubber hose feeding the fuel-pump, and simply blow back. (Cut one end at an angle, so you know which end hasn't been in petrol.)
A means of regulating pressure & cleaning the fuel at the same time, is to provide a return pipe from the carburettor back to the tank. Old Mitsi Mirages (Colt in UK and Oz?) had a banjo-union with an extra port exiting on the high side for the return. A filter somewhere in the loop completes the job. The return pipe should be a size up compared to the feed; use a high point in the return to set the pressure-head at the carb. This would beat any mechanical regulator setup!
Date: Thu, 25 Mar 1999 08:43:26 +0000
From: Andrew W. MacFadyen
Subject: [imps] Re: Fuel system
Interestingly mid 70s Hunters and Avengers (and also many BL models) had bad problems with debris from the fuel tank clogging filters and fuel pumps because some idiot decided to start painting the inside of the fuel tanks, the cure introduced by Smiths who made the tank sender unit was a nylon mesh filter that fitted over the suction pipe end inside the tank. This has the major advantage of being to a large extent self cleaning, as fuel sloshes about the tank removes any flakes of paint that accumulate on the outside of the filter. This modification was 100% successful and the original part was available under a Rootes part number for retro-fitting to any car that has this problem and should fit any UK car of that period. An alternative would be to fit a 'bag filter' in the same position.
Date: Thu, 25 Mar 1999 20:12:17 +1100
From: Mike & Tich Marsh
Subject: [imps] Re: Fuel system
I can't remember if I've already posted this before, but a classic problem in South Africa was with Imps that had stood in yards for a long time and had their petrol tanks used as a spare store for lawnmower fuel! Continual inserting of bits of hard cheap nylon hose pipe (for siphoning fuel out) through that twisty shaped filler hose resulted in a collection of fine scrapings of thin plastic swarf in the tank which worked their way down the fuel pipe. One such Imp (affectionately known as the Cockroach) when later put back on the road suffered intermittent fuel starvation which had us foxed for weeks till we found out what it was. Solution turned out to be a stirrup pump at the carby end and a bit of piano wire from the fuel tank end, mighty pumping, and a real scary explosion that blew petrol and little bits of plastic all over the garage :) Cured the fuel starvation... one of those little mesh filters would have been really good.
Date: Thu, 25 Mar 1999 10:25:07 +0000
From: Andrew W. MacFadyen
Subject: [imps] Re: Fuel system
My grandfather had problem with a customer's Austin 10 it would run fine for weeks then cut out and then start again only if left for 2 hours it turned out to be a Tram ticket floating about the fuel tank.
From: Gary and Carol Henderson
Date: Thu, 25 Mar 1999 23:00:23 +-1200
Subject: [imps] Re: Fuel system
Then there was the V8 Pilot which would always get a stopping lurgi after 200 miles - a piece of well-preserved grass in the pickup!
Seriously, does anyone know a readily available filter which will bung straight in? (I don't like opening tanks for any longer than I can avoid.) Otherwise, I'll research it when/if the blow-back trick doesn't do for long enough between episodes. The trend has actually been the other way - monthly has grown to about 3-month intervals over about 18 months.
I guess the paint was to boost the pathetic zinc-plate, after Cadmium was banned.
From: Nickcleak@aol.com
Date: Thu, 25 Mar 1999 16:06:51 EST
Subject: [imps] Re: Fuel system
Yes a filter is available for the Volvo 340 which is about 40mm long and 17 mm dia. It has an 8 mm hole in the end to press over a metal fuel pipe.
A piece of 8mm pipe could be fitted verticly to the Imp fuel outlet adapter, but of course the last 13mm of fuel in the bottom of the tank may not be picked up.
Part number 3342840
From: Gary Henderson
Date: Fri, 26 Mar 1999 14:54:07 +1200
Subject: [imps] Re: Fuel system
This gets close to the reason why Model A Fords always came with a layer of gravel in the bottom of the tank - the pickup was elevated to avoid sucking water...