1997 Volvo 855 GLT Misfires (P0300, P0301,... ) at hot start

[jreed]

Just wanted to post a photo of the little jumper that I used to keep the car running for a few days before I installed the replacement fuel pump relay. This worked great, just as you said cn90! Thanks.

Jumping the 87 and 15 sockets with a short length of wire

FuelPumpRelayJumper87to15.jpg (170.01 KiB) Viewed 792 times

[cn90]

jreed,

On the issue of jumper wire, I use a jumper with a built-in fuse holder, about $3 at local autoparts store.

In the photo below, I used a 15A fuse because this is what I had lying around lol (1st photo), but the correct fuse for fuel pump is 20A (2nd photo):

[mecheng]

This is a good idea to check, my solder joints were cracked on the two leads for coil on the bottom side. There were not pure circumferential cracks that stranded me like w/ my Honda but under a small magnifying lens you can see them. I also added some solder to the top of the joints, there isn't really any and it helps support the coil. Be careful not to add too much solder as the traces are quite close, I had to suck some solder at one point and use my point tool to make sure there are no shorts to clean between the traces. I found it best to used a soldering iron, the gun is not narrow enough.

Here are pics after the work is done.

[cn90]

And carry a jumper wire (with in-line fuse) in the glovebox.
Don't forget to carry a set of Torx keys too.

These items can get us home safely!

[mecheng]

And carry a jumper wire (with in-line fuse) in the glovebox.
Don't forget to carry a set of Torx keys too.

These items can get us home safely!

I always keep some extra paper clips in my car, I figure they are small enough to act like a fuse as well.
You can use them on virtually any connection.

[cn90]

Search forum, but someone used paper clips as jumper for fuel pump, only to find out when he touched the paper clip, he almost burned his fingers!

[mecheng]

Search forum, but someone used paper clips as jumper for fuel pump, only to find out when he touched the paper clip, he almost burned his fingers!

I don't see how that is possible it is positive on both sides of the terminal. You are not touching ground at the same time

[cn90]

...I don't see how that is possible it is positive on both sides of the terminal. You are not touching ground at the same time

Please see the attached pdf for Bosch fuel pumps.

From an electrical standpoint, a device, whether it is a fuel pump, a blower motor, or a headlight bulb, it is a resistor. So, whether we like it or not, it is "grounded" to the other side. Basic electrical circuit theory.

The 850 and S/V70 series has the outlet diameter of 8-mm, so the current draw is approximately 6.5A.

I do not know the gauge of the standard paper clip, but my guess is that: it is smaller than the typical fuel pump wiring (maybe ? 14-gauge). So when you use paper clip to jump something, be careful as the current may exceed the paper clip current carrying capacity ---> it heats up.

Personally, I think a jumper wire with in-line fuse is cheap and safe.

[mecheng]

...I don't see how that is possible it is positive on both sides of the terminal. You are not touching ground at the same time

Please see the attached pdf for Bosch fuel pumps.

From an electrical standpoint, a device, whether it is a fuel pump, a blower motor, or a headlight bulb, it is a resistor. So, whether we like it or not, it is "grounded" to the other side. Basic electrical circuit theory.

The 850 and S/V70 series has the outlet diameter of 8-mm, so the current draw is approximately 6.5A.

I do not know the gauge of the standard paper clip, but my guess is that: it is smaller than the typical fuel pump wiring (maybe ? 14-gauge). So when you use paper clip to jump something, be careful as the current may exceed the paper clip current carrying capacity ---> it heats up.

Personally, I think a jumper wire with in-line fuse is cheap and safe.

I agree a jumper is better, I am just surprised. Both sides of the fuse are Positive otherwise you would have a short. The fuel pump has its own ground that has nothing to do with the fuse wiring.