95 Caravan blows fuel pump fuse...replaced fuel pump twice

I've got a 94 Dodge Grand Caravan 3.3L, front wheel drive.
I was going down the highway when the fuel pump fuse blew.
I immediatetly put in another fuse and it blew after turning
the ignition on, but before cranking the engine.

I towed it to the local Tuffy's and they swapped out the fuel pump
(I had them install an Airtex fuel pump ($160) instead of the
regular AC Delco fuel pump ($350) they normally install.) They
also replaced the 6ft(?) wiring harness that connects to the
pump assembly, and they swapped out the fuel pump relay. (They
normally replace the fp,relay, and harness, even if only one of
these is bad.)

It ran okay for about 6 hours then blew the fuel pump fuse again.
After about an hour, I installed another fuse and it ran fine.
I took it back to the shop to diagnose why the fuse blew though.
It ran fine for them for a while and then blew the fuse. They
mentioned that the new wiring harness also melted during testing.
So they again replaced the wiring harness and fuel pump with another
Airtex fuel pump.

It ran okay for about 4 hours out of the shop and then the fuel
pump fuse blew again.

One thing I have noticed and the mechanic noticed as well, if you
start the engine while it's cold, there isn't any problems. If you
turn the engine off and then restart it while it's still warm, the
fuel pump fuse will either burn out immediately upon turning on the
ignition, or it will usually be fine until you try to crank the
engine again.

The mechanic also disassembled the fuse block under the hood but
didn't see any problems.

The guy I spoke with at O'Reilly Auto Parts was the one that suggested
the Airtex fp. He mentioned he had 5 years experience with Carter fp's
and 5 years experience with Airtex fp's and said he has had about half
as many returns with the Airtex units.

I've found a post by someone else that seems to be having the same
problem, with the same year model:

http://www.autowhiz.com/messageboard...ge.php?id=1709

Any ideas would be appreciated.

Thanks,
Jeff

How about the fuel regulator on the fuel rail being shot and pump
pressure going through the roof, thus causing too much current draw,
thus blowing fuse etc. Of even a plugged filter.. Have a pressure check
at the fuel rail.. Maybe even the return line to the tank is plugged.
Just a guess.. Lottsa luck.. ;-)



eff Frohwein wrote:
> I've got a 94 Dodge Grand Caravan 3.3L, front wheel drive.
> I was going down the highway when the fuel pump fuse blew.
> I immediatetly put in another fuse and it blew after turning
> the ignition on, but before cranking the engine.
>
> I towed it to the local Tuffy's and they swapped out the fuel pump
> (I had them install an Airtex fuel pump ($160) instead of the
> regular AC Delco fuel pump ($350) they normally install.) They
> also replaced the 6ft(?) wiring harness that connects to the
> pump assembly, and they swapped out the fuel pump relay. (They
> normally replace the fp,relay, and harness, even if only one of
> these is bad.)
>
> It ran okay for about 6 hours then blew the fuel pump fuse again.
> After about an hour, I installed another fuse and it ran fine.
> I took it back to the shop to diagnose why the fuse blew though.
> It ran fine for them for a while and then blew the fuse. They
> mentioned that the new wiring harness also melted during testing.
> So they again replaced the wiring harness and fuel pump with another
> Airtex fuel pump.
>
> It ran okay for about 4 hours out of the shop and then the fuel
> pump fuse blew again.
>
> One thing I have noticed and the mechanic noticed as well, if you
> start the engine while it's cold, there isn't any problems. If you
> turn the engine off and then restart it while it's still warm, the
> fuel pump fuse will either burn out immediately upon turning on the
> ignition, or it will usually be fine until you try to crank the
> engine again.
>
> The mechanic also disassembled the fuse block under the hood but
> didn't see any problems.
>
> The guy I spoke with at O'Reilly Auto Parts was the one that suggested
> the Airtex fp. He mentioned he had 5 years experience with Carter fp's
> and 5 years experience with Airtex fp's and said he has had about half
> as many returns with the Airtex units.
>
> I've found a post by someone else that seems to be having the same
> problem, with the same year model:
>
> http://www.autowhiz.com/messageboard...ge.php?id=1709
>
> Any ideas would be appreciated.
>
> Thanks,
> Jeff

Don Ocean wrote:
> How about the fuel regulator on the fuel rail being shot and pump
> pressure going through the roof, thus causing too much current draw,
> thus blowing fuse etc. Of even a plugged filter.. Have a pressure check
> at the fuel rail.. Maybe even the return line to the tank is plugged.
> Just a guess.. Lottsa luck.. ;-)

Thanks Don. I had them check all of these but no luck. They gave up
on it since the problem is very intermitent and they weren't getting
anywhere.

LUCKILY, they gave me the ALLDATA wiring diagrams they had printed out.
(They got these from alldata.com, I assume.) In these diagrams, I found
the fuel pump relay. This part of the electrical system was missing
from the Haynes manual I bought. :-\ With the ALLDATA daigrams I noticed
the oxygen sensor also connects to the fuel pump relay output. After
inspecting the oxygen sensor cable leading to the oxygen sensor, I
noticed what appeared to be friction-related wear of the cable exposing
wires.

I'm not 100% sure that is the problem, but so far with the oxygen sensor
unplugged I haven't blow any more fuses.

Thanks,
Jeff