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Loss of power problem is back!

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carrottop

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Loss of power problem is back!

I posted this issue a couple of months ago and attributed it to water in my 1/4 tank of gas that accumulated over winter. Wrong! Keoke thought it was my Pertronix.

Well I drove my Tri-Carb about 12 miles this morning. All was smooth as silk. Then, after 2 miles I started to lose power, kept running by calling for more fuel but eventually I had to stop as I couldn't get any power and she finally stalled out. Waited a few minutes and she started right up but only had weak power, rough idle and I could hear the ping as I rode along at 10-20 mph to my destination another 10 miles. Tonight on the way home, same issue but rough idle at start with less than ideal power, nursed her 6-7 miles until she had nothing at all and stalled out. Pushed her off the road, waited only 2 minutes and she started immediately with full power and smooth as silk all the way home, another 5 miles.

Called Pertronix, they claim when the unit fails, it dies completely. They thought I might have a low voltage or ground problem. Everything looks fine in my dizzy. And all wires look tight and secure. New rotor, new plug wires, new plugs, new fuel filter all done to solve this problem to no avail. Flame thrower coil installed at same time as the ignitor.


So now what do I try? Go back to points?

Eric
 
Re: Loss of power problem is back!

If the same thing happened in cooler weather, I suggest reinstalling the points and see what you get. If there is an intermittant problem with the Pertronix, this is the best way to find it.

I would look inside the distributor cap, looking for cracks or moisture.

You could be experiencing vapor lock, this problem is especially severe when driving in hot weather with winter gas in the tank. What is the fuel pump doing? Is your fuel cap properly vented? The problems with vapor lock can come and go very quickly, making them hard to diagnose.
 
Re: Loss of power problem is back!

I don't remember where the Healey's mount their coils. Had this problem many a time on the Jags. The coil was in a hot spot on the engine and the connections were expanding and causing it to loose power and stall. Would start back up after a minute or two and then as soon as you were up to speed down it would go again. Crimped all the terminals and tightened the nuts and all was well again. Might check for a stuck float too!
 
Re: Loss of power problem is back!

Sounds like intermittent fuel starvation to me. Check for a crimped fuel line, dirt flooding out float needles, dirt under pump valves, etc.
 
Re: Loss of power problem is back!

Eric, sure there are a lot of things that could cause this but why not start at the beginning? How are you checking your battery voltage? How are you checking your grounds? Regardless of what you've done to it , if it were in my shop I'd start with the battery , its connections and move to the distibutor and do the same thing. I'd take out the Pertronix for now and install new points, condensor , rotor and coil. Check closely the small wire that grounds the points plate to the distibutor body. Nine times out of ten you'll find and fix a problem like this by thoroughly inspecting every detail of the system. You'll need a 12v test light and a multi meter. Maybe something you assume is ok and looks ok really isn't. The check for tight valves etc. then a stuck float or bad flexible fuel line. I've got about 3500 mi. now on my restored tri carb and it seems to keep running better all the time. Good luck.
 
Re: Loss of power problem is back!

Eric,

I concur with Rich in that it sounds like fuel starvation. I expect you have something partially blocking the line and moving in and out of position.

I had a similar situation when a piece of silicon, previously used to seal the gas gauge sending unit, fell into the tank and eventually was sucked into the gas line. Being a relatively small piece, the silicon would work its way into a position of almost completely blocking the fuel line and stave the engine. After a short engine turn off, the silicon piece would float to relieve most fuel line blockage and allow the engine to run fully.

Since the silicon piece was highly mobile and situated before the pump, it took two search attempts to produce a small membrane of silicon that, at the time, I questioned was the cause of my problem. My experience of having no problems after provided my answer.

Good Luck,
Ray (64BJ8P1)
 
Re: Loss of power problem is back!

I had the exact same problem with the wifes MGB. It turned out to be the shielded fuel hose on the suction side of the pump was cracked and allowed a very small amount of air to enter the system. The engine would run fine for about a half mile and die. It would restart and do the same thing over again. New line and problem solved. PJ
 
Re: Loss of power problem is back!

Thanks for your comments. Will check battery voltage and ground contacts this weekend. But I'm leaning towards the fuel starvation ideas. Will remove the fuel filter and check the lines. Also, I noticed my fuel pump is clicking more often then in the past. Getting clicks every 2 seconds on a repeated basis which I don't recall hearing before. I know it's under the passenger rear seat, but how do I get at it? I noticed 2 screws holding the seat down.

Regards,

Eric
 
Re: Loss of power problem is back!

Eric , I've had problems with the reinforced neoprene hoses also. The ones Moss supplied lasted only 4-5 yrs. I replaced the liner only , keeping the outer sheath for an original appearance. I've also had a few grose jets stick shut on the tricarb even though I use Sta-Bil in the gas in the fall. Kevin
 
Re: Loss of power problem is back!

Undo the screws on the rear passenger seat behind the driver [lefthand drive] remove the seat and voila, the pump is right below the opening.
 
Re: Loss of power problem is back!

I had a similiar problem with my BT7 last year. My problem was some gunk in the bottom of the tank was sucked up into the pump and caused a bit of a clog, reducing flow. It would shut down and after sitting for a couple of minutes it would start up again as the pump was able to get enough gas into the carbs to fill the bowls, then it would repeat the cycle.

Flushed out the tank, placed a 2nd fuel filter inline between the tank and pump, solved the problem.

Jim
 
Re: Loss of power problem is back!

JBlubaugh said:
I had a similiar problem with my BT7 last year. My problem was some gunk in the bottom of the tank was sucked up into the pump and caused a bit of a clog, reducing flow. It would shut down and after sitting for a couple of minutes it would start up again as the pump was able to get enough gas into the carbs to fill the bowls, then it would repeat the cycle.

Flushed out the tank, placed a 2nd fuel filter inline between the tank and pump, solved the problem.

Jim
Click to expand...
I had a very simliar problem back in the 70's. The sump was plugged, or should I say "partially plugged, part of the time"? Disconnect all the fuel lines and blow them out. Be sure to remove the tank and clean it out too.
My pump would stop pumping because the obstruction made it think that the carbs didn't need anymore fuel. I can't begin to tell you how long it took to troubleshoot and actually fix this problem!
Patrick
 
Re: Loss of power problem is back!

So I checked the battery voltage. It's fine. Ground contacts in and around distributor also fine. Looked at fuel pump. It's an old SU, with older looking hoses. Replaced the hoses and installed a see thru fuel filter entering the pump to check if any crud shows up. Decided to check the in line fuel filter by the carbs and oops, it was in backwards. Not a good thing. Replaced it and started her up (with filter in the right way). All remained fine for the first drive. Fuel filter by pump is clear with pump clicking quite a bit though. Strange though that the pump looks more like the BJ8 type pictured in Moss but how can that be? Considering a replacement by the catalog suggests the new square type which doesn't look anything like mine.

Will take a few trips this weekend and continue to check the pump but for now all is OK. Could it have been the reversed filter? Embarrassing....

Have a great 4th all!

Regards,

Eric
 
Re: Loss of power problem is back!

Eric,

I appreciate your frustration.

Your pump is a possible replacement (AUF300 chosen for its availability at the time and increase in output volume to better serve your tricarbs. Within the unit, a check valve and screen allow clean fuel to pass one way. The small screen within this model SU pump could have trapped some crud and, intermittently, becomes partially blocked. Again, intermittently, sufficient back pressure may not be building on the outlet and the pump continues to try. If your problem continues, I would suggest you check the internals of your pump.

Good luck,
Ray (64BJ8P1))
 
Re: Loss of power problem is back!

It could be a failing Pertronix from RFI noise that's blocking the Pertronix from reading its own signal. I put a lot of DM6 Helaey distirbutors back to poitns to avoid this issue.

It could also be an innefective engine ground strap. Run jumper cables from the engine to the body/battery and see if it smooths out. The distributor may be grounding well to the engine, but sensor vpoltage bleed can easily overcome an old original engine ground strap!!!

Moast commonly a bad plastic component which expands with heat can cause a failure. Check and replace the rotor, cap, even plug wires if the problem is temp related.

Then again, it could be as simple as a corroded ground wire or low voltage to the fuel pump.
 
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