Cutting out when radiator fan kicks in

[tubbyG]

As the title suggests, once up to temp the fan will cut in as it should but after 30 seconds or so of it running, the engine cuts out on me.

I thought maybe that the battery was at fault as it was pretty drained and only just got it started, but the same issue occurs with another fully charged battery fitted.

Anybody experienced this before, thoughts on where to look?

Wiring to/from the fan switch looks good, no breaks that I can see.

If the fan motor is on the way out, could the fan be drawing to much current that there is not enough for the plugs? ............. or should I be looking at other parts?


cheers

[SCHWARTZ]

I would just put the fan on a seperate relay away from the loom take the feeds off the alternator, unless you're keeping it o/e

[Brigsy]

The question is does the engine idle ok before fan cuts in? If the idle is poor then that may be your problem.

[LiamR]

Got an AFR fitted???

What is the RPM when the engine is idling?

Does it sound like a strong idle or is it struggling and just hanging on without stalling?

[tubbyG]

Thanks for the input.

It seems to idle well with no fluctuations in rpm, it possibly takes 15 mins or so for the fan to come on. Up to this point it idles as it should. I have idle set to 800rpm, might be worth bumping this up a touch and see

I will give the idle jet a clean out, and wire the fan directly and see what the outcome is.

[tubbyG]

Got an AFR fitted???

What is the RPM when the engine is idling?

Does it sound like a strong idle or is it struggling and just hanging on without stalling?

once the fan kicks in, it idles fine for a short while before starting to hunt slightly, rpm drops and afr's go lean then it dies

[tubbyG]

Just been out to investigate, so I have wired the fan direct to the battery & cleaned out the idle jet.

Idle set to 1k with an afr of 14.1/5.......... but still cuts out.

engine began to hunt after 10 seconds when the fan came on but AFR's stayed steady before it died

[Brigsy]

Maybe check the alternator is working properly with a test meter. If its hunting i would say its carb related though. Maybe air leak on carb base?

[LiamR]

Can you try a different carb??

Or as mentioned above, check the alternator output.

[TNT ANDY]

I was thinking this 1st - if it runs ok without the fan running it would indicate an electrical fault. get a volt meter on it when the trouble starts and see what the voltage does.

[Os8472]

I had something like this once, turned out to be a problem with the main power cable from the alternator to the starter motor, give that a check and clean up all your engine bay earths too

[tubbyG]

Thanks for the input chaps. I will get my meter home from work today and have a quick check over things tonight and report back.

I did suspect the carb at first, as I had it off a few weeks ago to change jets and a few gaskets - maybe it is becoming blocked, but I have been cleaning it through every time it dies on me.

[TopCat]

Sounds like it could be a charging issue to me mate, if the fan cuts in and is draining the amps from the battery then the engine will stall. Check your alternators out put, then check your earth like others suggested. Put a jumper cable from your battery to your chassis- see if it does it then

[tubbyG]

Had half an hour this evening to check things over. All earths were tight and intact, cable from alternator to starter was good. So I cleaned through the idle jet again and got it running,

14.4V out the alternator so that was good. Drove up the drive to the back of the house and waited for the fan, when that started the voltage dropped slightly but nothing significant. But it didnt cut out this time

So a partially blocked idle valve would cause this? ....Im not overly convined. Nonetheless I will be checking all the wiring when i take it off the road and strip it down for the winter refresh

Thanks for all the suggestions