PDA

View Full Version : Fuel pressure



drpete
19-10-2015, 08:29 AM
I've been having some issues with my motor and just when I thought she was right.....
I need some thoughts on this. oh, by the way, it's a 100hp yammy fourstroke 1999.
Had the carbys all off and sonic cleaned. And new leads. Ran like a bag of crap afterwards.
Took it back to the dealer and the fuel was full of rubbish so the carbys came off and were cleaned again (twice in the one week).
I remove and scrub the fuel tank spotless and blast the lines all clean too.
New fuel in through a Racor micro fine funnel.
Got amongst the whiting over the Rous on Saturday and everytime I went to start her after a drift, she won't start.
Have to squeeze fuel up everytime. Then it runs rough as guts till the pressure builds up, and she's fine again.
The whole time when she's off now, there's a constant soft ticking noise from somewhere too (that may not be related at all, but it could also be the sound of fuel draining back through a check valve I suppose). Which is what I think it is, a leaking check valve. Coz I can't find any external leak. All the lines we had off are tight as can be and there's no fuel anywhere.
It could also be something as simple as the no-return valve on the bulb failing slightly (although that WOULD be a bit of a coincidence, but not impossible).
I'll call the mechanic when they open, but until then...any thoughts at all?.....
Thanks
Petey

shaungonemad
19-10-2015, 09:20 AM
There are some dodgy bulbs out there I have even had one straight out of the package that was no good. It should be easy to check just take it out of the line and squeeze it and put your finger on the end it should stay flat on one end but not the other

drpete
19-10-2015, 09:42 AM
Yeah I'll do just that.

Watto79
19-10-2015, 12:30 PM
Air in your lines?!

drpete
19-10-2015, 01:08 PM
Air in the lines is POSSIBLE but it doesn't really explain why it's leaking down or why it runs fine after the fuel pressure is taken up.
Once the air was forced out, it shouldn't get back in again without a vacuum leak SOMEWHERE is the system. At least, that's my imperfect reasoning on it... :)