Endless engine bleeding post fuel filter change?

[jdavid]

I just replaced the primary and secondary fuel filters on an atomic diesel 5424 on a 1981 O’Day.

I did not prefill the primary fuel filter.

I have been bleeding the engine for about two hours and I still have air in the fuel system.

Any ideas?

[Cheechako]

You're saying it wont start? or saying it runs rough and you cant get the air out?

Assuming it wont start: I'd like to have you prefill both filters if possible. If air in the lift pump, it cant pump anything up.
If you have flex lines before the filter near the tank, a squeeze bulb between the tank and filter is handy for these issues.

[Emmalina]

Sounds like you chomped an o ring !

[tkeithlu]

Ditto on both of the above. It sounds like you either have too much air in the system for the lift pump to work at all or you are sucking air into the system, with an O-ring being a good candidate. So, the recommendation is that you disassemble the system, prefill everywhere that you can, and reassemble with great care. I like the squeeze bulb suggestion. In that case, open a bleeder as near to the injectors as you can and then push the air out with the bulb. Good luck with it.

[Engine man]

Silly question - how do you know you have air in the fuel system?

NOTE - when installing a new secondary fuel filter, always install it dry, then bleed the system, as detailed in the owner's manual. Here's why -

Prefilling the secondary filter with fuel results in that filter, in effect, being bypassed. This means you just allowed contaminants to flow past the filter, and into your fuel injection pump. Joe

Originally Posted by jdavid

I just replaced the primary and secondary fuel filters on an atomic diesel 5424 on a 1981 O’Day.

I did not prefill the primary fuel filter.

I have been bleeding the engine for about two hours and I still have air in the fuel system.

Any ideas?

[FPNC]

Are you using the manual fuel pump on the side of the block?

[Lepke]

If the engine ran fine before the filter change, then the filters are the problem. It's common for the filter seal to be the air leak. Something that helps the seal is to grease the seal or oring.

Replacing the manual pump with an electric makes bleeding easier. An electric pump can be installed inline with the manual pump. Either pump will pump thru the other.