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Is it my fuel pump? Any thoughts?

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kurts100

kurts100

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Driving home from a car show in my 100-4 and the car started running like it was only on 2 or 3 cylinders. Barely could make it up hills. Stopped and changed spark plugs, filled the gas tank with premium and started off again. Nothing changed. Still ran horibly, however at an idle it ran fine. I nursed it along and then thought to pull out the choke. Ran much better. Not 100% but got me home using full choke. I've always had problems with this new fuel pump (lucas w/ points). Would stop for no reason and I'd beat behind my seat and it would start up again. I've cleaned the points and actually put very small amount of clock oil on some of the pivot points of the point mechanism. That has helped with it just stopping on me.

I'm thinking that the pump isn't pumping the proper pressure, since it runs at idle but not well when you give it gas. Since it ran much better on choke thought it might be starved of fuel without choke because of a bad fuel pump.

Any thoughts. I'm thinking about switching fuel pumps to the electric solid state one that Moss sells. I bet this one I have now doesn't have 2000 miles on it. Thanks! Kurt
 
A suggestion, examine all your piping, hoses. Knew a car that went through three pumps, all replaced by the owner, before I got a chance to examine and saw that when the pump was pushed up into place it kinked a hose.

Then measure your pressure and volume(output) going to the carbs...
 
Another recent thread suggested the posibility of trash being sucked up by the pump from the fuel tank (a problem I once had as well).

If it is still running badly, disconnect the pipe leading to the pump (from the tank) and give it a puff of air, either the compressed variety or from the lungs. If there's any resistance, take note. Once you can easily blow through it, reconnect the lines and see if it drives any better.

If there's any sheets of scale (or sloshing compound) floating about the tank, it gets sucked up partially or completely blocking the pickup tube. Boiling out or replacing the tank are the only reliable solutions.

If you need a new pump, here's my recommendation: https://www.pegasusautoracing.com/productdetails.asp?RecID=2698

1107.JPG


Personally, I use the "blue top" version, but with a Holley regulator (the cheap round chrome style often do not work at all).
 
kurts100 said:
...

I'm thinking that the pump isn't pumping the proper pressure, since it runs at idle but not well when you give it gas. Since it ran much better on choke thought it might be starved of fuel without choke because of a bad fuel pump.

...
Click to expand...

That doesn't make sense to me. If the pump is having trouble delivering adequate fuel without 'choke'--which actually only lowers the jets allowing more fuel from carbs to engine--pulling the choke knob would either have no effect or make the situation worse; i.e. if the pump can't deliver enough fuel for normal running it'll be worse for a full-rich condition. Seems to me like you have an issue in the carbs (sunk float, sticky float needle, crud in the jets, etc.), although it sounds like you might have pump issues as well.
 
SU pumps are tricky to adjust properly, and have been known to come out of the box not properly adjusted. I sent the following to the email list a while back, maybe it'll be of some use here:


"I stumbled across something I thought I'd pass along. You may recall I've been having trouble with the fuel pump in our BN2/100M. I've got two pumps, one a 'factory' SU electronic, and one that came with points that I retrofitted with an SU electronic kit. Both pumps exhibit erratic behavior--sometimes behaving like they should and sometimes pumping quickly, then stopping, then pumping quickly, ad infinitem.

We've checked the lines--no leaks--and, suspecting a fracture in the tank pickup tube, tried pumping directly from a pail of gas. No change. Suspecting flooding, I installed Grose jets in the carbs and, although any minor flooding seems to be mostly controlled, the erratic pumping goes on.

What I found is, possibly, a good/better method for adjusting the diaphragm. I've always adjusted them 'by the book;' something like screw them in until the throwover mechanism just stops throwing over, back off 4 'holes,' etc.; and (I think) Rich C has suggested adjusting one hole looser than the book. The electronic kit I retrofitted came with a (fairly thick) feeler gauge, and I adjusted the pump per the instructions. The pump sat unused for several years while we started the restoration, and when the time came to install it it wouldn't fire at all. In a hurry, I bought the factory SU electronic and figured I'd revert the other to points for a spare.

In trying to solve our erratic pump behavior, I decided to give my retrofit another shot. I didn't have the feeler gauge, so I connected the pump up to a car battery and played with the diaphragm adjustment. You'd expect that if the diaphragm is set too tight the pump won't work properly, but I found that at even one hole too loose the pump wouldn't work either (this may be a 'duh' for some, but I've been working on these pumps for years and it was a revelation for me). There is about a 2-3 'hole' range where the pump will operate at all, and one where the pump seems to work the best.

So ... my suggestion is when 'tuning' an SU pump--this should work for a points pump as well--set the diaphragm per the book, then connect to a 12V battery and set for the most robust pumping."
 
I will second Bob on the choke logic.

Low fuel flow can also be caused by blockage of the little screens on the pump and carb inlets as well as a clogged fuel filter if you have one.
 
Thanks for the input! I'll spend some time checking things out this weekend. Will check all the things mentioned. Will check filters in pump and carbs, blow air into gas tank to clear screen on intake (tank was redone and lined with some type of red coating several years back), take carbs apart and check floats and valves. Then will try and check pressure in pump and adjust the diaphram. Can anyone suggest an easy way to do that and what should the pressure read?

Also, on the Facet pump, is it similar to the electronic one Lucas has with no points, in the way it works. After all the problems I've had with my current FP, just want the most reliable one I can get.

Thanks,

Kurt
 
kurts100 said:
Thanks for the input! I'll spend some time checking things out this weekend. Will check all the things mentioned. Will check filters in pump and carbs, blow air into gas tank to clear screen on intake <span style="font-weight: bold">(tank was redone and lined with some type of red coating several years back), </span>take carbs apart and check floats and valves. Then will try and check pressure in pump and adjust the diaphram. Can anyone suggest an easy way to do that and what should the pressure read?

Also, on the Facet pump, is it similar to the electronic one Lucas has with no points, in the way it works. After all the problems I've had with my current FP, just want the most reliable one I can get.

Thanks,

Kurt
Click to expand...
RED FLAG!

Can't answer your question about the fuel pump__historically speaking, things that just work I know very little about, it's the troublesome components that I have memorized.

With that in mind, I wish I knew nothing about my Healey :wink:

Something I did note though, the pump I linked to is for negative ground, but I expect they have something for positive ground cars as well. Even their solid-state "cube" pump have been dead-reliable in all the applications I have used them for.
 
Wanted to thank everyone again for the advise. I spent this evening on the car. Took the fuel pump out to check filter and diaphram. Diaphram was fine but the filter had some crud in it. Also blew air into the gas tank thru the fuel line. Figured if there was crud in the fuel pump, there must me the same on the screen at the fuel pick up in the tank. I checked who had done the tank 8 or 9 years ago and it was a company called Renu. Everything still looks in tact inside the tank as far as the red coating they put on the inside. Tore the carbs apart and checked floats, needle valves, filters in the lids of the fuel reservoirs, blew air down the jets incase something was stuck in the small hole in the reservoir that delivers the fuel. Everything checked out fine. Car started right up and once warmed up, had good power without using choke. My guess is that it was the dirty screen in the fuel pump and possibly the pick up in the fuel tank. Never realized there was a screen on the end of that.

Next project is a leak at the thermostat housing that I've resealed twice and it's still leaking. Very annoying as it blows a small amount of antifreeze thru the louvers on my hood onto my windshield. Have a feeling the thermostat housing isn't perfectly flat. When I put a straight edge from side to side I can see alittle daylight. You would think that using RTV and a gasket would take care of it but apparently not....Always something with these cars.

Kurt
 
Any thoughts. I'm thinking about switching fuel pumps to the electric solid state one that Moss sells.

Well quit thinking about it and do it!!-
-Just make sure it says "SU" on the box and the pump's label.

I bet this one I have now doesn't have 2000 miles on it.

Well you can mount it on the wall as a reminder of what not to put in the Healey.

Thanks! Kurt--You are welcome----Keoke
grin.gif
 
Already ordered Keoke. This one has stopped on me way too many times. I think I bought this one with points probably 10 years ago. I don't recall the electronic solid state one being offered back then. Are they relatively new? Finally, some piece of mind.

Kurt
 
Even though it sounds like the pump, I would have made a check of the distributor, especially the cap and rotor.

brg Lars
 
Already ordered Keoke. ________ :thumbsup:

Keoke :laugh:
 
Would a simple go/no-go check of the fuel pump and tank by disconnecting the fuel line from the carbs and running the pump into a jar be of help?
 
Stretch said:
Would a simple go/no-go check of the fuel pump and tank by disconnecting the fuel line from the carbs and running the pump into a jar be of help?
Click to expand...
Yes, there's actually a specification of how much fuel it should pump in a specified amount of time. Check your w/s manual.
 
According to Norman Nock's Tech Talk book the fuel pump should pump approx. 1 quart in 1 minute. Never did get to that now that it's back to running good. That probably would have been my next step.

Kurt
 
FYI, that Facet pump pictured looks identical to the 40 year old Bendix Pump I have in my Healey. My car came with that Bendix, one experienced old British car guy told me years ago not to change that Bendix, they had a great reputation.

Well, I have had my car for over 35 years and that Bendix just keeps working just fine. I had an MG before and had to change the SU's regularly, they rarely worked for more than a year or two.

Bendix is long gone, that Facet is probably now made in China. But if it is the same design, I think it will work well in most Healey's.

Sounds like your problem is not the fuel pump, I think you may have dirt in the bowls or a plugged filter.

Bill
 
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