Engine Heat Empties Fuel Pump.. Any Ideas

[altezzaclub]

So, the Golden Girl is a dead stock KE70. Sometimes I jump in, it fires up, runs for 30seconds to a minute and dies. About as long as it takes to empty a carb bowl full of fuel. It won't restart. The fuel filter is empty, so is the pump. Solution is to put the filter inlet line into a jar of petrol, pour some down the carb and refil the carb, pump and filter. It makes a shopping trip into an anxious gamble..

 

It can be fine for a month or two, then do it.

 

After running around town for a while I park it, lift the bonnet and see the fuel filer filling up more. Then bubbles come from the outlet end into the filter. The fuel filter is filling up because it is upside down. When it is right-way up the vapour comes in the top and pushes all the fuel out the bottom and back along the line to the tank. Then the pump struggles to suck it all back before the battery goes flat.

 

The fuel pump looks new, so I think the previous owner was chasing this problem. It seems to look and work OK, but I don't know if it is correct for the car. Its hard to see if it has an insulating block as the car has aircon and the bracket covers the pump. That extra heat sink after 20minutes of running won't be helping either.

 

Current solutions are- mount the filter higher as a tiny surge tank, or make a little surge tank up on the firewall., or stick in an electric pump. I'm not getting too carried away as I'm changing the motor earlyish next year, but I wondered if vapour-lock was a problem in K motors.

[ke70dave]

I'd be trying a spare pump before trying any crazy go nuts modifications.

 

Also perhaps try cracking the fuel cap to let air in/out. perhaps the fuel tank vent is blocked causing vacuum and the tank pump can't keep up?

[parrot]

Millions of reliable Corollas tell you the design is sound, so it has to be a fault somewhere between the tank and carb, rather than a need to re engineer the car. Which I don't doubt would be a work of art, just unneccessary.

 

Surely it has to be a transient blockage somewhere?

[GJM85]

My money is on a cactus pump. I went through two pumps in two years and that was enough for me so I went electric.

[Taz_Rx]

Fyi the 'insulator' between the pump and block isn't for heat insulation, it makes the throw of the pump arm correct onto the Cam. If you don't use it you'll snap the arm off the pump in a minute or 2.

As above, might be a vacuum issue. Does it have a standard charcoal canister setup? If so maybe disconnect it for a minute so you know the tank can breath...or remove the fuel cap as above.

[altezzaclub]

Also perhaps try cracking the fuel cap to let air in/out

It does hiss, but I can't tell if its pressure or vacuum in the tank. The Girls KE70 has no problems like this, and it also hisses when you take the cap off the tank. Do the tanks go under partial vacuum when running?? so the tank sucks the fuel back along the line? or are they pressurised by the return line from the pump??

 

Surely it has to be a transient blockage somewhere?

Possibly in the charcoal filter line. Watch your filter after you turn the car off and see if fuel gets pushed back by the pump. Once mine is running its fine, its not a blockage causing it I don't think. The fact that bubbles come back into the filter is interesting, if they were vapourised petrol you would expect them to collapse when they meet cooler liquid fuel.

 

My money is on a cactus pump.

Well, I wondered if its not a stock unit and not designed for the car. Maybe the inlet valve is not sealing correctly and letting fuel leak backwards That would also explain why it can't suck fuel very well when there is air in the suction chamber.

 

Fyi the 'insulator' between the pump and block isn't for heat insulation, it makes the throw of the pump arm correct onto the Cam.

Well, I knew that, but that's part of wondering if this is a stock pump. Did they find the "best fit" pump that runs OK but doesn't have any insulation... nah, just paranoia!

 

Does it have a standard charcoal canister setup?

Yep-

 

OK, I'll pop the pump off sometime and check it out carefully. Then I'll just check the lines to the tank and make sure the tank can breathe OK. Maybe change the filter, run it w/o a cap on the tank for a while....

 

But first I have to get the wife's SSS N14 running, it just died last week and there are no engine codes showing up on the SR20!

[tojo2]

does it make a difference how much fuel you got in the tank ?

 

Just thiking this might happen if you got a smal leak on suction pipe inside fuel tank.

,

[Banjo]

Does the fuel pump currently on the KE70 have a return line back to the tank, or is it a simple 1 line in from filter, 1 line out to the carby ?

 

Both types were fitted to various KE Series models, but each works in a totally different way. Never had this problem, other than the ocassional sticking needle in a carby due to poor fuel.

 

However, I think we are all familiar with the "hissing" sound when we remove the tank lid to "fill up", which is normally more prominent on a hot day, so my guess is, the tank pressurises, rather than creating a vaccum.

 

Cheers Banjo

[altezzaclub]

does it make a difference how much fuel you got in the tank ?

I don't know, I've haven't kept track of that. I think it happened the other night (after a couple of months being fine) because we parked it on a steep sideways slope, passenger side down.

 

Does the fuel pump currently on the KE70 have a return line back to the tank,

Yep, both KE70s in the garage do, both being '83s but one is a flatfront XX and one a slanty CS. The return line comes off the pressure side of the pump and when the car is running it returns fuel to the tank.. well, at idle anyway!