3tj fuel pump problems

[peebee25]

Hi all,
I hope someone is able to help !!!!
I have a 1990 3tj that has been stripped and rebuilt and has been running with a few teething problems ...
it has now decided to present me with another... it will start ok and run ( a bit lumpy as the carbs need synching properly) but the fuel pump doesn't pump on initial power up like it used to , the pump is ok as it works when connected direct to a battery,the relay has continuity across the terminals and it does click on and off again as it should after initial priming. Could the cdi be stopping it from working while the engine is running? if so , is there anybody who could test and possibly repair it if needed? once i have worked out how to do it i will put some pics of my fizzer on .

[laminator]

Hello Paul, pull up a chair and grab a beer.

Have you tried putting a multimeter across the pump terminals when you turn the key, and again when the bike is running, ie does the pump get any power when the bike is running.

If the bike runs, although lumpy, is there a reason you think the pump isn't working? It could just be float heights, jets blocked, mixture, balance, etc.

Pics

(Get an account at a hosting site like photobucket, upload your pics, then copy the link into your post)

[peebee25]

hi thanks for the reply and info about posting a piccie or two.
yes i have tried with a meter , i used to get voltage when the ignition was turned on then going off when the relay shut off, if i connect the meter to the black and blue wire on the pump loom and to the negative on the battery, i get a voltage reading . i am thinking i may have knackered the ecu because reecently i tried to be clever and do away with the reserve switch function by using the supply to the fuel sender via the fuel pump using a relay to light up an led on the dash , before this the pumnp was working as it should!!! oops. thats why i was hoping someone could test and maybe repair my ecu..

I am now going to try the piccie thing ... fingers crossed

[peebee25]

chuffin eck it worked this is my finished fizzer ... all show and no go at the mo!!!

[Evilchicken0]

The bike looks really good - maybe some stickers on the tail.

So I take it you've put everything back to standard ???
Clean the carbs and check the float vavles - balance them and then see if it still does this. Renew the / check the fuel filter and see if the fuel tank breather is blocke or the fuel line kinked. I don't think it's the cdi if it was the pump wouldn't work at all.

[thunderace]

[CMSMJ1]

Fag packet bikes are cool.

[Taggyd]

i had this with the race bike,got fed up of chasing it and wired a new circuit via a fuse and it's own switch.

[peebee25]

it seems more electrical than carbs, i have stripped the carbs many times and cleaned them , the diaphragms are all ok, new (bigger) jets because the down pipes have the exup removed, the exup motor is still plugged in and whirring like a whirring thing when the ignition is turned on. it starts fine( when the battery isn't low on juice). i cant seem to get out of my mind that i may have buggered something important ..... its very frustrating cos last summer it eventually ran ok without breaking down!!! just needed jetting cos of the pipe..

[peebee25]

Finally solved the fuel pump problem, after spending £100 on a replacement ecu!!!!!!! i was convinced that i had blown mine up somehow, however plugging in the replacement never fixed my problem...... s**t!!! i thought then as if by magic when i moved the fuel pump it fired into action!! my problem all along was just a knackered plug on the wiring loom , one new plug later and it all runs lovely, until after a run it now cuts out ! is this never ending? now i have to strip the the chuffin carbs again to check float heights, i hope thats all it is.




ANYONE WANT TO BUY A FIZZER!!!!!!!!