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fuel pump?

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M

maynard

Yoda
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Coming home from work today, my 94 V12 atarted to act up. It
started running very rough and backfiring. AT first I thought it
was the Marelli problem, but it was backfiring on the left bank.
Having no choice, and not far from home, I had to drive it. When
the engine hits 2500 rpm, everything is fine.

I'm beginning to think it is one of the fuel pumps. Yesterday, for
the first time in a long while, I drove without the radio on and
heard the fuel pump running. Is this a possiblity? Can I check
the fuel pump by switching the leads from one to the other?

Any suggestions not only will be greatly appreciated but will earn
the suggestee an adult beverage (or 2) when in the Chicago area.
 
You can check the fuel pumps with an independent 12 volt power supply by connecting the 12 volts directly to the pump connections. I have unscrambled a V12 fuel pump problem previously but I am relying on my memory and it has been a while. I think that one of the pumps is used as a main pump all of the time and operates through a relay. The second pump is switched on when the engine demands higher than normal performance and consequently fuel. The second pump is turned on by a logic module which I have forgotten the name of. I can look it up in the documentation if you need that information. My take on your problem is that your main pump might be developing insufficient pressure but it is overcome by the secondary pump over 2500 RPM. I hope this helps. Jack.
 
Tried switching the fuel pump leads and no dofference. The left bank is still dead.
Now am back to thinking an ignition failure. Replaced the rotr (I had a spare) no change. However, when I looked at the inside of the cap, I noticed the ring for the B bank rotor pickup was somewhat out of place. I have ordered a new cap and will let you know what happens. STill don't know why the engine runs fine at over 5o rpm.
 
I'm having fuel delivery problems on my alfa... I'm glad it only has "one bank". /ubbthreads/images/graemlins/smirk.gif But I keep reading this as my interest in v-12 cars are great.
 
Update. I couldn't just sit there, I had to do something. I swapped the fuel pump leads, and there was no change. I swapped the coil plugs and the dead bank went from the left to the right. I have ordered new coils and I'll let you know what happens.
 
Don't know, maybe you're just psycho (opps, I mean psychic).

What threw me was the one bank cutting in at 2500 rpm. Never had a coil on an electonic ignition car exhibit that behavior.
 
like someone I know says, "Jaguars have many surprises built-in". And curiously, as of last week I have seen a flood of leaking coils and just plain going-bad ones. Solar Storms causing this? Then, my 1965 S type still has the original coil dated 1964 which still works fine. Check the WIRES, the coil might be fine. /ubbthreads/images/graemlins/thumbsup.gif
 
Replaced the coil this afternoon. Engine now runs like it is supposed to. However, I now have an FF19 code. I had forgetten to reconnect the vacuum line to the cruise control before I started it. Is the code related to any of this or the backfiring when the coil died? Where do I start?

Thanks
 
Is it possible for a coil to do the opposite? IE: work fine at idle and low revs, but cut out at 2500-3000 rpms.
 
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