FUEL PUMP / SUPPLY QUESTIONS......

[NardisCNC]

Hello, My '66 Midget w/1098 has a problem.... I just replaced the Points, Condenser, Dist Cap, Wires, Plugs, and Coil because they were long due for a change. Now when I go to start it, it will fire right up and run smooth as silk for a few seconds and then just slowly die like it has ran out of fuel. It will refuse to start again at this point. If I try it the next day the same thing happens, it will start right up again but die very shortly after.

With the bonnet open I can see the fuel filter. When I first go to start it (when it fires up), the filter appears to be about 1/2 full. Once it dies, this is what it looks like and the fuel level will not change:

What should this look like or how full should it appear when working correctly?? This car is now Negative Earth by the way and the previous owner installed a new electric fuel pump a couple years ago that I think he got from Victoria British. When you have the ignition on you can hear the fuel pump motor running, but the above picture is all you get once it dies.

How do I properly test the fuel supply? Thanks in advance for any help!!

-Nardis

 

[Sarastro]

Fuel does not move well through these modern paper filters. I suspect they're intended for a system with more fuel-pump pressure. Also, the fuel today seems to form vapor bubbles more easily than in the 60s. I've been told that it's caused by anti-knock additives (e.g. butane) that are more volatile, now that lead compounds are no longer used.

In any case, as soon as the filter element gets wet with fuel, and a little vapor builds up in it, you get a bubble, and fuel just doesn't get through it well. Arguably a form of vapor lock.

One possibility is to get a higher-pressure fuel pump (maybe ~6 psi? Just a guess) and a pressure regulator, with the filter between the pump and regulator. This will reduce the tendency of vapor bubbles to form, and may force the fuel through the filter even if they do. Another is to use a wire screen filter, which won't remove particles much smaller than dead squirrels, lost car keys, or buffalo chips, or do what my ol' TR4 had, a sediment bowl and no filter.

At present, I have a low-pressure Facet pump with a screen filter on its input (the recommended one), a Holley pressure regulator, and no filter at the carbs at all. I know, this is living dangerously, but some risk that something will get plugged up is still better than a dead certainty. At some point, I'll probably get a higher pressure pump and reinstall the filter.

 

[Jim_Gruber]

I'm running into the exact same issue trying to get Bugsy my '68 Sprite going. Same problem starts and then cuts out as if starved for fuel. Now I replaced hte fuel pump that had worked fine for 9 years+ late last summer with an Airtex Low Pressure pump from Advance Auto, $55.00 3 p.s.i. & I can get the number, exact replacement. So I suspect I am having some sort of fuel delivery problems getting from the tank to the pump. Pump runs but I can hear it struggling to try and deliver fuel. Again filter shows half empty and I can see it spurt trying to pump fuel.

I do have an inline filter on the pump itself and I suspect the inline filter may itself be plugged or the filter screen inside the tank may be plugged. I can recall changing the tank float 8-9 years ago and inside of tank looked clean then but I haven't had it apart since then.

After cogitating on this last night here is my course of action I'm planning:

1) Change out inline filter in front of fuel pump and try to determine if inline filter is blocked. These are cheap from auto parts place.
2) IF problem disappears immediately and pump starts going tic-tic-tic correctly I will suspect rust in the tank.
3) Drain tank and filter gasoline once dry to see if rust can be detected. A coffee filter works fine for doing this I suspect.
4) If rust is detected, pull tank, check strainer, and then make a decision on boiling out tank and coating inside with POR-15 or replacing tank.

Since I had this issue last summer and pump failed, before I added paper filter like you have at the carb, I'm suspecting my issue lies upstream in the tank.

Anyone got the name of the source other than the usual sources that was selling Spridget fuel tanks.

 

[JPSmit]

My sense here is that you eliminate one variable at a time. I took out my filter completely and actually replaced it with a piece of clear hose so I could watch flow. The problem didn't go away, so, kept on looking (it was air elsewhere BTW) so, filter is back in and running fine - mind you, it's also lying down so gravity isn't an issue getting the fuel up. Somewhere I read that it takes a lot of continuous pressure (like 300lb if I recall) to keep the filter full of gas, so, that by itself isn't the problem.

The fuel system itself is not complicated. Can only be - tank to fuel line (including venting) fuel line to pump, pump, pump to carb, carb, or filter wherever it is. There are no other options. The trick is to go one at a time staring with the easiest.

 

[DrEntropy]

Pump supply should be somewhere around a pint in under 60 seconds, at the carb supply line.

Ethanol is eeevile. But more likely responsible for any "vapor lock" issues than anti-knock additives.

Carter has an in-line pump unit which seems to work very well in LBC's, Part #P60504. The metal bodied Facet low pressure one from AZ or other Big Box as well.

...but check delivery volume of the unit you have there first.

 

[Jer]

Disconnect the line from the outlet side of the fuel filter, and then hang your fuel line (with filter attached) into a container, turn the fuel pump on & see if fuel is flowing into the container, if fuel is flowing then the issue probably isn't the pump/filter, if nothing is flowing then disconnect the filter & repeat test, if fuel flows then the filter is the issue.
Obviously be sure you don't spill fuel all over the engine bay & don't leave your ignition on for very long (while testing fuel pump) as this can cause damge to your points etc.
From what you mention, I would be checking the ignition parts that were installed, if the car was running fine before the tune-up, there is a 99% chance it isn't the fuel system, as nothing was touched there...

 

[dklawson]

As a footnote to the advice above, use a COARSE filter before the fuel pump and a FINE (like you have) filter after the fuel pump. This is particularly true for the Carter pump that the DR. recommended above. (Available through Amazon and some NAPA dealers). The Carter pump is cooled by flowing fuel and if you plug a fine intake filter, you can overheat and melt the pump before the float bowls can run dry (BTDT). The filter shown in your photo looks like the fine air cooled VW type I have used for years. They are more than adequate on the discharge side of the pump. However, as I said before, do not use them on the intake side of the pump.

The pickup screen in the tank could be plugged so you may want to try blowing "back" into the tank with the filler neck open. Also check that the tank vent is open and that you are NOT drawing a vacuum inside the tank when it's been running for a while. Also, if the float valves in the carb are new OR if the car sits a lot, you may want to remove the float bowl lids and check that the needles in the float valves are clean and free to move up and down. Sometimes a slight tolerance mismatch can be corrected by gently scraping the "corners" on the sides of the float valve needles. Gum and varnish on the float valves can also stick them closed. Lastly... if you have Grose jets instead of traditional float valves... try going back to regular float valves again. Grose valves caused me nothing but problems.

 

[jlaird]

Again I would bet that it is the float valves. Remove free, clean a bit and try.

 

[Jim_Gruber]

Jack,

I had local LBC guy take my floats apart and reset the needle valves to proper clearances, added shims to both front and rear to get it right. Can starts easily far easier than before I don't think it is floats listening to the sounds the fuel pump is making. It really sounds like it is straining and hesitating like htere is a load on it. Fuel filter by the carb is not full and I can see it pulsing rather than a steady stream. I won't have a chance to get into it until the weekend. Lots of time to cogitate on this one.

 

[jlaird]

One of your float valves is stuck in the closed position. Easy check, three screws and you can peak inside easly.

Car will start and run with one stuck closed but will not run over about 1500 rpm worth talking about.

If it takes you 15 min to check I would be susprised. One of the float chambers will be empty.

 

[Jim_Gruber]

Ok that will be my first check and that won't take even 5 minutes to check. Thnaks I'll provide a full report.

 

[Jim_Gruber]

OK so both floats are empty, back to my original theory of pump sucking and pumping but being unsuccessful in pumping fuel. No time till this weekend for further look at it.Turn key, pump pumps but watching glass filter reveal little if any fuel making it to the carbs. Again either line is blocked from crud in the tank, at least 4 gallons of fuel in there to transfer or small filter before the pump is plugged. Jack I have the same pump on Bugsy as you are using for Ms. Agatha.

 

[HAN8L1965]

I am wondering if you don't have dirty fuel before the pump, possibly within the tank at the tank filter. When you leave the car off the possible debris is left to float away from the intake, then when you turn it on it clogs the system after a few minutes. I run a paper filter up front and have had no problems. I also have a heavier duty filter between the tank and my pump. I am running the low flow square box filter we ahve all discussed here. In the end I think you may have a dirty tank.

Mark

 

[Guest]

Possibly, but a pin hole in the line b/w tank and pump will do the same thing ( loose, line fitting at tank?). What about his cap, is it supposed to be vented?

I would ( myself persoanlly) suck on the tube gentle and slowly to see if you have a restriction. Carefull not to get gas in yer hole. ( or in you lungs as that might kill you). What I do is draw a quick vaccum w/ my mouth, then quickly cover the hose with my tongue and see if it holds a vaccum.

Depending on what you get, blow back'rds through it. Does it go bubble bubble?

Last but certainly not least, did you pinch the steel fuel line with a jack or stand? Hit something on the road and smash it flat?

Wanna ruin someone's week? All it takes is a hammer! :wink:

 

[texas_bugeye]

Ok here’s a thought on mine I purchased a new fuel tank from Vicky Brit years ago about a year later I had sort of the same symptoms thought it was the fuel pump kinked line air leak fuel filter clogged the gambit . What it ended up being was the pickup was either bent or crack or badly assembled.
The way I figured it out was it would start to mess up at below 3/4 tank.
Try topping the tank and see if it works. What the heck a couple of gallons in the tank is worth a shot to see if it is the problem.

 

[Guest]

BUT.......just try one thing at a time.

 

[Jim_Gruber]

Thanks guys. Will have a shot at looking at things hopefully tomorrow night. After 8-9 years since I've looked inside that tank, and since this fuel pump has maybe 5 hours at most worth of running on it, I'm inclined to believe I've got an issue upstream from the pump. Could be a pinhole in a line although I replaced all of the rubber lines back there last fall when I replaced the pump.

I'm thinking crap in the tank has plugged the mini filter that is integral to the pump itself. Again I'm planning on draining the tank as well and will put the gas through a coffee filter once it is drained and transfer it to the lawn mower gas supply. Will be curious if I find large amounts of rust in there that come out of the tank. If so might be boil out and POR-15 time. More to follow.

 

[JPSmit]

might be that the hard lines are clogged

 

[Guest]

transfer it to the lawn mower gas supply. If so might be boil out and POR-15 time. More to follow.

NO.... DO NOT DO THAT !!!!!

I used to put "old" fuel in my $6000 Exmark till it gummed up a valve and bent a pushrod, not to mention started gumming up the carb. The fuel I used didn't seem that old and it ran pretty well, till bits got bent and gooey. My mower never sits year round so it didn't get worse while it was in there.
You want to kill shrubs, ant, weeds or paint it on the neighbor cat's bung hole, fine. Don't put it in your equipment.

 

[NardisCNC]

OK..... sorry to waste anyone's time on this one. However what I thought to be the potential source of this problem was a complete illusion. The fuel supply is good and strong. I disconnected the line (after the filter pictured) and ran it into a bottle, it filled up in just a few seconds.

I'll start a new thread will all the details of what happened building up to this point, and what happened as my engine ceased to run. Thanks again!! - Nardis