mysterious fuel starvation

Thanks, Scott. Mine's a driver, too. So, anything to bullet proof it I'm for. New pump on order. I will put my orignal SU lovingly into a well-marked box for future generations, along with the original radiator, header tank, coil, etc. wjd

Warren,

Ok, that's a good description.

The pump I installed is a modern pump. I find it depends on what kind of jag person you are -- some owners would never fit a modern pump. I enjoy driving my car, so it's a modern pump for me.

I'm not sure if company plugs are ok here or not, but I've got no affiliation or anything with these guys, I just think they're a good company.

I got mine from the Little British Car company, lbcarco.com

Their solid state electric pump kit runs about $50. They've created a kit specifically for LBCs, 2.5-4.5 psi, for carb cars. Even my local Advance Auto parts has a generic electric pump on the shelf, which is like $35, but I put the LBCarco kit in my 70 FHC, because it is a low pressure pump. Some electrics can be as high as 9-10 psi.

It may be a little louder than the SU, and I can hear a little hum when it runs, but I don't find it objectionable. The kit comes with a mounting ring, and I installed it right in place of the SU in my FHC with no issues.

Check out their website, and you'll see a pic of the kit. It's under 'specials', and 'low pressure fuel pump'.

My apologies to the moderators if my plug for lbcarco is not allowed - please delete my post if so. I've dealt with them on parts, and they're a good company.

Good luck
Scott

1970 FHC, driver.

"Cures the problem" was a bit of shorthand for email. In full, what happens is this: The engine starts to starve and then quits, although its still turning over because the clutch is engaged; as this happens I move the choke up halfway while I'm decellerating (usually from 65-70 mph); by the time I'm down to about 45 (several very long seconds), the engine picks back up and will run fine -- though I usually bail out from the highway and am driving on "surface streets" at lower and more variable speeds. It does not happen frequently, nor only on hot days. I can't hear the fuel pump, but couldn't even if it were exceedingly loud because of the usual wind, engine, and transmission symphony. The pump is stock, but I had it rewired by an armature shop -- as I've done with all things wound that bear the Lucas name -- and the pump points are fine. It ticks normally whenever I first turn the key, i.e., when I can hear it. Never checked the pressure. I've thought about installing a modern pump independent of this issue only because I find the stock design to be strange. In fact, if you've got a suggestion for a modern pump that I could plumb in permanently I'd love to hear it. wjd

No, perhaps you are right. It still doesn't explain why if you choke the carbs, the problem is gone.

Perhaps a little more detail on how that "cures the problem." Does that mean if you leave the choke halfway on that the car runs perfectly on the highway the whole time? If it does, than it can't be a fuel pressure or pump problem - there's plenty of fuel there.

How about after it stalls on the highway - do you just restart and drive away? Can you hear the fuel pump pumping? Could it be vapor lock? Does it happen every highway trip, or just on hotter days?

Are you running the stock fuel pump? Pressure good? Perhaps fit a modern pump temporarily and try it out - see if it changes. Perhaps the stock pump is stuttering.

Scott

1970 FHC, driver.

Scott, thank you for the thought.

They were rebuilt about 3000 miles ago, and the car is very responsive across the throttle range. I wouldn't think all three carbs would lean out simultaneously due to jet or float valve wear.
wjd

I'm pretty sure on my 70 FHC, that the left side board is indeed screwed down.

As for the fuel starvation, you say you can choke it and it cures the problem. I would say then that the carbs indeed have fuel in them, and it's just an overly lean condition.

How long since your carbs have been rebuilt?

Scott

1970 FHC, driver.

Warren,

In my '69 roadster and '70 coupe, the left board just comes right up. It's possible your board is wedged in there tight, but it would simply pull up. Check around the edges to make sure it's not screwed down and just try giving it a few carefully placed whacks with a mallet to loosen it up. It may be caught under the trim or might be rusted in place.

Steve

Steve,

How do I remove the left trunk board to get full access to the inspection plate? wjd

Steve,

How do I remove the left trunk board to get full access to the inspection plate? wjd

Warren,

Hope that helps. Please report back and let me know if that's the problem. You might also check the plastic tube between the tank and the pump. If it's gotten soft it could be collapsing, or it could be clogged as well.

Steve

Thanks, Steve. Sounds exactly like the problem. wjd

Warren,

I had a similar problem when I bought my '70 coupe a few years back. Turned out it was the pickup in the tank. Over time, the pickup tube got corroded, reducing the diameter of the tube. At lower speeds, the flow was sufficient to keep the car running. As speed picked up, the flow was not enough to keep the carbs filled, and the engine would die out. After it sat and the pump could suck enough fuel to refill the bowls, the car would start again. But I'd start driving, and it would die.

I'd suggest removing the inspection plate on the tank and checking the pickup. Also, there is supposed to be a screen on the end of the pickup, which itself can become clogged. It's a good time to check that, and to inspect the sump and inside of the tank for corrosion as well. I ended up having to have the tank pulled, boiled out, and coated. Plus, the pickup tube needed to be cleaned out as well and a new strainer screen installed.

Hope that helps.

Steve Weinstein, JTC-NJ
'70 XKE FHC, '69 XKE OTS