Technical Idles but won't accelerate

[FR85]

Hi All,

Out for a spin yesterday, all was going well and then all of a sudden lost power, car would idle but as soon as I introduced a bit of right foot engine would splutter to the point of dying.

Fuel pump is working, did a test on that and I changed the plug leads as I had a set with me.

I'm leaning towards coil as the car has a rev gauge fitted and it was going mental.

Car is a 500f with a 650 engine and it does have an electronic ignition fitted.
I don't think it's heat related as it does the same thing from cold.

I have been meaning to do the float level but I'm holding out for an ethenol friendly kit!

Thanks

Gav

 

[Toshi 975]

Hi All,

Out for a spin yesterday, all was going well and then all of a sudden lost power, car would idle but as soon as I introduced a bit of right foot engine would splutter to the point of dying.

Fuel pump is working, did a test on that and I changed the plug leads as I had a set with me.

I'm leaning towards coil as the car has a rev gauge fitted and it was going mental.

Car is a 500f with a 650 engine and it does have an electronic ignition fitted.
I don't think it's heat related as it does the same thing from cold.

I have been meaning to do the float level but I'm holding out for an ethenol friendly kit!

Thanks

Gav

Worth checking that the carb is not loose or leaking at the base

 

[FR85]

Worth checking that the carb is not loose or leaking at the base

Will do, thanks!

Would that be a gradual fail or all of a sudden? 50mph to farting along....

G

 

[Toshi 975]

Will do, thanks!

Would that be a gradual fail or all of a sudden? 50mph to farting along....

G

I had the carb nuts loosen on me twice. On tick over the engine was quite stable and the induction suction kept the carb in place. When you tried to accelerate the carb wobbled and sucked in air at the base causing the engine to die.

 

[FR85]

I had the carb nuts loosen on me twice. On tick over the engine was quite stable and the induction suction kept the carb in place. When you tried to accelerate the carb wobbled and sucked in air at the base causing the engine to die.

Thanks! Will start there first and then explore the coil

 

[gordinir8]

Have you tried pull the chock and see if things getting better? Might be a blocked jet.

 

[Goldnrust]

I'm leaning towards coil as the car has a rev gauge fitted and it was going mental.

Presuming the tach going mental is a new thing, I’d certainly be leaning towards an ignition issue. No carb issue should make the tach jump.

Likewise, depending on what triggers your tach a failing coil could cause it to jump, an issue with the ignition pickup would definitely cause the Tach to jump. Do you have the old points system to drop back in just to test it?

 

[FR85]

Have you tried pull the chock and see if things getting better? Might be a blocked jet.

Choke makes no difference, still falls down and I pulled the idle jet and it was perfect.....

 

[FR85]

Presuming the tach going mental is a new thing, I’d certainly be leaning towards an ignition issue. No carb issue should make the tach jump.

Likewise, depending on what triggers your tach a failing coil could cause it to jump, an issue with the ignition pickup would definitely cause the Tach to jump. Do you have the old points system to drop back in just to test it?

Tach is a new symptom, all happened at the same time. The ignition pickups generally tend to cause grief when they're roasting, this is doing it from stone cold.
I do think you are along the right track. I've points and a condenser out of a 600/850 but I'm not sure if they're the same!
Tomorrow in the garage will tell a tale.

Many thanks!

G

 

[FR85]

So, popped a Lucas DLB105 coil in and no difference.

Carb was on there good and tight but I pulled off the rocker cover and carb, going to try and get a kit for it and start over. Opened the float chamber and it looks brand new and also the float isn't full of fuel. I think someone has been in there in the last 5 years as it looks squeaky clean.

Also going to buy a couple of sets points and a condensers, once the carb is rebuilt and valve gapping is reset I'll start from there.

I have two carbs, both say Weber 28 on them but one has 1 after the 28 and the other has 5, what does that indicate can I ask?

As always, that's for you time and knowledge!

Gav

 

[FR85]

Just had a thought, I should have disconnected the tach from the coil to eliminate that as an issue.

Could a bad tach cause running issues??

Gav

 

[Goldnrust]

It doesn’t seem likely that the tach would cause the issue, but if it’s triggered directly from the negative post of the coil it is possible, if somethings shorted out inside the tach, or more likely there’s a short in the wiring between the coil and the tach.

Disconnecting it from the coil is an easy test at least.

Sorry can’t help with carb stuff, I’m not familiar enough with the specifics of this carb. The ignition stuff is a bit more general.

 

[FR85]

It doesn’t seem likely that the tach would cause the issue, but if it’s triggered directly from the negative post of the coil it is possible, if somethings shorted out inside the tach, or more likely there’s a short in the wiring between the coil and the tach.

Disconnecting it from the coil is an easy test at least.

Sorry can’t help with carb stuff, I’m not familiar enough with the specifics of this carb. The ignition stuff is a bit more general.

All help is welcome help!

It's all stripped now so once I've the carb cleaner and rebuilt I'll try that first. Would be something as typically simple as that!!

Thanks!

G