FUEL PUMP WILL NOT PRIME??
Discussion
hi all, can anyone help me on this one, my 350i would start up great,but then now it takes some time turning over before it fires up then on to some missing and poping then runs ok, the only thing I can say is, that the fuel pump does not (prime) run for 3-4 seconds before I would turn key all the way to start it,if so what could this be all releys click ect;s any help would be great superwedge, 
Edited by superwedge on Monday 11th June 22:18
Hi Dave.
What is your CO...mine was doing it and the AFM needed adjusting as it was running badly lean...I fitted a cigarette socket plug from an old lamp I had and attached it to a spare CTS plug and long length of wire, I ran it into the bulkhead next to the throttle cable.
I plug it in...turn the key...she starts....count 1...2...and remove...happy days...
What is your CO...mine was doing it and the AFM needed adjusting as it was running badly lean...I fitted a cigarette socket plug from an old lamp I had and attached it to a spare CTS plug and long length of wire, I ran it into the bulkhead next to the throttle cable.
I plug it in...turn the key...she starts....count 1...2...and remove...happy days...
My top tip for starting EFi is to crank it first for 1-2 seconds with full accelerator, stop cranking but leave ignition on, wait 4-5 seconds, then it will fire up on the next throw of the ignition switch.
This gets the pump running and the fuel rail up to semi pressure, the delay seems to allow the rail to fill in case it has vapour in it.
Otherwise I would be cranking for a full 6-8 seconds before it would catch, my way saves a lot of strain on the battery and starter.
This gets the pump running and the fuel rail up to semi pressure, the delay seems to allow the rail to fill in case it has vapour in it.
Otherwise I would be cranking for a full 6-8 seconds before it would catch, my way saves a lot of strain on the battery and starter.
adam quantrill said:
My top tip for starting EFi is to crank it first for 1-2 seconds with full accelerator, stop cranking but leave ignition on, wait 4-5 seconds, then it will fire up on the next throw of the ignition switch.
This gets the pump running and the fuel rail up to semi pressure, the delay seems to allow the rail to fill in case it has vapour in it.
Otherwise I would be cranking for a full 6-8 seconds before it would catch, my way saves a lot of strain on the battery and starter.
I tried this and many other methods...For some reason mine needs a squirt of extra fuel to first start...Its gradually become longer and longer to a point that it would crank for nearly a whole minute before firing...everything checks out okay and the fuel rail operates at the correct pressure with no leaking back from injectors or reg...Mine became progressively lean over a year but since the AFM was set to the correct value...she pulls like a train...I still need a extra dose of go go juice in the mornings though....This gets the pump running and the fuel rail up to semi pressure, the delay seems to allow the rail to fill in case it has vapour in it.
Otherwise I would be cranking for a full 6-8 seconds before it would catch, my way saves a lot of strain on the battery and starter.
This was before...
https://www.youtube.com/watch?v=YvL4sn1qS5M&t=...
And this was after..
https://www.youtube.com/watch?v=qQUTblbqmvA
https://www.youtube.com/watch?v=YvL4sn1qS5M&t=...
And this was after..
https://www.youtube.com/watch?v=qQUTblbqmvA
I agree with Adam. Sounds like the fuel rail is taking a while to come up to pressure, maybe you have a small leak on one of the fuel pipes. Mine did this for years, if the engine was warm it took forever for the engine to catch and then it rarely ran cleanly for the first few seconds, I had to give a small amount of throttle to help it start.
I have since removed and replaced all the high pressure lines including the short injector pipes and the problem has completely disappeared. Check those short injector hoses, they are prone to weep when they get old and it is only apparent when first starting as the leaked fuel vaporizes instantly when it is warm.
Hope this helps.
I have since removed and replaced all the high pressure lines including the short injector pipes and the problem has completely disappeared. Check those short injector hoses, they are prone to weep when they get old and it is only apparent when first starting as the leaked fuel vaporizes instantly when it is warm.
Hope this helps.
I agree with Adam. Sounds like the fuel rail is taking a while to come up to pressure, maybe you have a small leak on one of the fuel pipes. Mine did this for years, if the engine was warm it took forever for the engine to catch and then it rarely ran cleanly for the first few seconds, I had to give a small amount of throttle to help it start.
I have since removed and replaced all the high pressure lines including the short injector pipes and the problem has completely disappeared. Check those short injector hoses, they are prone to weep when they get old and it is only apparent when first starting as the leaked fuel vaporizes instantly when it is warm.
Hope this helps.
I have since removed and replaced all the high pressure lines including the short injector pipes and the problem has completely disappeared. Check those short injector hoses, they are prone to weep when they get old and it is only apparent when first starting as the leaked fuel vaporizes instantly when it is warm.
Hope this helps.
pasogrande said:
Don't the V8s have an accumulator just after the pump to keep the system primed?
Hi mateyNo...The fuel regulator holds the pressure for a few minutes...you can test the holding pressure in the system...the stall pressure...return etc
Mine did it but all my fuel pressure..Injectors..pump...regulator were all good...my AFM slowly got worst and was running badly lean...Its strange as I had more RPM but less torque...when the fuel was sorted out the rpm went down and the torque went up...
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