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Engine sputtering...

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Wana

Wana

Jedi Hopeful
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OK Gurus. My BJ8 has run perfectly since I got it two years ago. I installed a Pertronix ignition right after I got it, two years ago. I put a new set of spark plugs in it a couple of months ago during Spring maintenence. Yesterday I went to pick up my son at the pool, car running perfectly as usual. I sat at idle for about 10 minutes while waiting for him. On the way back home the engine suddenly started sputtering or missing when I accelerated. It idled fine at the stop lights, but had a noticeable miss when underway and under power.

Battery is fully charged, tank is full of gas. Starts right up every time.

Any suggestions on where to start trying to diagnose the problem?

Thanks! Wana
 
Could be early signs of fuel pump going out. I would also check any filters in the fuel line.
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This kind of thing is usually the carbs or some other fuel-system problem. Could also be ignition, I guess, but probably not; if it were ignition, you'd probably have at least some missing at idle. First thing is to disconnect the fuel line at the carbs, direct it into a container (like a plastic bottle; for safety, not something very open) and make sure you're getting good solid squirts when you crank the engine. If that's OK, check the carbs for sticking pistons and dirt plugging things up--could be anywhere.
 
Thanks guys, hopefully I can dig in to it this evening. I'll let you know what I discover.
 
Hi Wana, after idling for 10 minutes in the heat, you may just have a little fuel "boiling problem".

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I recently had the same problem. It turned out to be the Petronix. Once replaced it worked just fine. This is my third one in 3 years, so I have had very little luck with these things. I now keep a spare in the boot.
 
Well, I unhooked the fuel line in front of the carbs and there seemed to be a good flow, although I don't have anything to compare it to as I've not done this before. There is an in line fuel filter before the carbs, so I replaced that with a new one thinking the old one may have been clogged. I went on a test drive and it seemed that the condition was better, but still evident. So, now I'm wondering if it might be a weak fuel pump - as far as I can tell it might be the original one still on the car. Would it be possible that the fuel line might be clogged a bit or restricted somewhere? How would I go about cleaning it out?

Thanks for all your help!
 
Rick G, when you experienced these sputtering symptoms did it just start all at once? Did it get worse or stay the same before you replaced the Pertronix unit? How did you know to do this?
 
Re: Update: Engine sputtering...

Took the Healey for a test drive this morning. It ran great, accelerating without any sputtering - for the first 5 or 10 minutes. Then the sputtering came back big time. I notice that it still idles fine, and I can rev it and it sounds fine, I can hold the throttle open a bit in neutral so that it is turning about 2,500 RPM and it seems to be running smooth. But, under acceleration it is definitely running very rough. No smoke coming out the tailpipe.

If the fuel pump is operating correctly, would I expect to see the in line fuel filter full of fuel? I noticed that is is not, it is only about 1/4 or less full while the car is running and when I rev the engine. With the engine off, when I turn the key I can hear the fuel pump ticking, but it seems to be ticking slower than normal.

I haven't tried replacing the Pertronix yet, not until I rule out fuel problems. What would you try next? Thanks! Wana
 
Re: Update: Engine sputtering...

Wana -

If you are getting sputtering on acceleration when warm, it sounds to me like you've forgotten to top up your dashpot dampers with dashpot oil. You have to check your dampers regularly....
 
Wana said:
Well, I unhooked the fuel line in front of the carbs and there seemed to be a good flow, although I don't have anything to compare it to as I've not done this before. There is an in line fuel filter before the carbs, so I replaced that with a new one thinking the old one may have been clogged up. I went on a test drive and it seemed that the condition was better, but still evident.-------------------That was a good move.

So, now I'm wondering if it might be a weak fuel pump - as far as I can tell it might be the original one still on the car.-----------It may be that the filters inside the pump are clogged up if there is loose debris in the tank.

Would it be possible that the fuel line might be clogged a bit or restricted somewhere? How would I go about cleaning it out?--------------------Disconnect the fuel line at both ends and blow it out with compressed air!.

Thanks for all your help!
Click to expand...

Just my thoughts.---Keoke
 
Re: Update: Engine sputtering...

Wana said:
Took the Healey for a test drive this morning. It ran great, accelerating without any sputtering - for the first 5 or 10 minutes. Then the sputtering came back big time. I notice that it still idles fine, and I can rev it and it sounds fine, I can hold the throttle open a bit in neutral so that it is turning about 2,500 RPM and it seems to be running smooth. But, under acceleration it is definitely running very rough. No smoke coming out the tailpipe.

If the fuel pump is operating correctly, would I expect to see the in line fuel filter full of fuel? I noticed that is is not, it is only about 1/4 or less full while the car is running and when I rev the engine.--------- That is consistent with my experience.

With the engine off, when I turn the key I can hear the fuel pump ticking, but it seems to be ticking slower than normal.-------This is also consistent with my experience.

I haven't tried replacing the Pertronix yet, not until I rule out fuel problems.
What would you try next?------------Put the points back in and see if it cures the problem!
Thanks! Wana
Click to expand...

Just some thoughts in passing---Keoke
 
any luck with a solution? i have a similar problem. the engine runs beautifully up to 2700 rpm and starts to run out of gas from that point on. i replaced the pump and still have the identical problem. i now am looking at the suction line between the tank and the pump. incidently, the pump runs almost constantly.
 
Hi Steve, How are your air filters are they clean??---Keoke
 
Wana,
From your description, " it runs and accelerates for the first 10 minutes and then starts to misfire ", it could also be caused by a bad coil.
Check the resistance of the primary side with a good zeroed in ohm meter. Do this one time when the engine is cold,
then check it again after the engine is hot and the problem
has returned. If there is any difference in readings between
cold and hot, you have found your problem. If no difference
in readings between hot and cold it is probably caused from something else but still appears to be related to the engine getting hot.
The primary side of the coil should be close to three ohms.
Ed
 
Hi Steve I missed that point about the pump runing constantly. You may have an air leak on the input side of the pump. If it is a new pump make sure the banjo fittings are not bottoming on the pump body causing an air leak.---Keoke

OH I forgot to ask what type seals are used at the banjo fittings on the pump.
 
I FOUND MY PROBLEM. the suction line from the tank is connected with a compression fitting. that compression nut had become loose (vibration?). after the fitting was tightened, the engine ran very well, except for a slight miss at 2700rpm and higher. i think that i'll have to check out distributer bushings for excess wear. the air filters are relatively clean
 
stevebj864 said:
any luck with a solution? i have a similar problem. the engine runs beautifully up to 2700 rpm and starts to run out of gas from that point on. i replaced the pump and still have the identical problem. i now am looking at the suction line between the tank and the pump. incidently, the pump runs almost constantly.
Click to expand...
If the pump is running constantly, your sucking air not fuel.
 
UPDATE: Engine sputtering...

Well, I've finally gotten time to go through the suggested items. I replaced the fuel filter, checked the fuel pump flow into a milk jug, replaced my Flamethrower Coil with the old stock coil and finally took the Pertronix out and put the points back in. The car still runs exactly the same - sputters a bit when I accelerate. So, I'm now wondering if it could be something with the carbs? As you may recall, this condition started suddenly, while ideling waiting for my son at the pool. The car had been running perfectly for 2 years, and as I pulled away from the pool parking lot I noticed the sputtering for the 1st time. And it now does it every time I drive it. It starts fine and seems to idle fine.

Any suggestions on what to check on the carbs (or anything else that might come to mind)?

Thanks! Wana
 
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