Wednesday, July 24, 2013

We have a car, and it finally works well

First, let me share the fuel pump saga.  The little episode the other day was the second time that the fuel pump just decided to not start.  It's never stopped while running, but failed to start twice.  And both times it has mysteriously decided to get back on the job some time later, again for no apparent reason.  My presumption was a subtly faulty rebuilt fuel pump.  Perhaps a bur that caused it to jamb, or maybe a flat spot on the armature?  So I called a local fellow Volvo nut to see if he had another pump I could try.  He did, so I hopped in the car and went of to get it.  After a quick swap out, I discovered that the "new" pump leaked around the electrical connector, just like the original one that was in the car when I bought it.  Not as much, but it still leaked.  So back to the rebuilt one.  I'm getting good a swapping pumps.

Next I called Hans at H&R Fuel Injection.  They have rebuilt a couple of mechanical injection pumps for Mercedes for me, along with a variety of other injection parts, fuel pumps, etc..  My question for him was whether he could rebuild one of the leaking pumps that I have.  After hearing where it was leaking, he proceeded to tell me how to fix it myself.  He said the electrical connector is a common leak point, and all you need to do is clean up the area and epoxy around it.  That's how they fix them.  It's worth a try as a side project one of these days.

All this left me with a fuel pump that sometimes won't start, rendering the car inoperative, with no solution other than waiting around for magic to occur.  Other than that, it's all back together and runs great.  For better or worse, I decided to drive the car back to Gloucester which is about 180 miles.  I figured as long as I didn't shut off the car, I'd be fine, right?  So off I went.

The first stop was to get gas, and the car was running so well that I decided to shut it off while I filled.  And it restarted just fine.  So far so good.  Then about an hour later, hunger and nature called so I made a pit stop, and again shut it off.  Big mistake!  I got back in the car, realized it has no cup holder for my drink, but went to get underway anyway.  Key turn, and no fuel pump hum.  Crap!  Well, with no cup holder I figured I really should eat before getting underway anyway, so I chowed down hoping magic would occur while doing so.  Occasionally I'd turn the key to see what would happen, and every time there was nothing but a relay click.

After eating I decided to test the stuck-fuel-pump theory and got out a screw driver to rap the pump body to try to free it up.  Whack, whack, but nothing.  Then I decided to play with the wiring a bit and tried jumping the fuel pump lead right to battery power and guess what?  The pump ran!  Ummmm, sounds like an electrical problem, not a pump problem.  That's actually good news.  A little more screwing around revealed a bad connection in the little accessory fuse box that feeds the fuel pump power line.  Some scraping and a new fuse and the problem is fixed.  That was the most productive break down I've every had.

The rest of the drive was uneventful.  Actually, quite pleasant.  I'm really liking how the car runs.


Anonymous said...


Just a tip in case your pump does die in the future. The motor from the later two port D jet pumps bolts right up to the three port mechanism. The advantage is that the later two port pump seems to be a little more common and cheaper.

Perhaps the best solution might be to find a readily available external mount pump like the Walboro GSL392. You would need to convert from the M10 pipe fittings to a barbed inlet and outlet; but, the price is cheap (about $110) compared to the price of the Bosch pump. I think that all you would have to do is cap the return line at the tank that comes from the overpressure relief port on the Bosch 3 port pump. If my pump dies in the future, I think that is the route I am going to try.

142 Guy

Peter Hayden said...

The rebuilt pump that I have is a two port model like you describe, and we capped off the unused overflow line when it was installed.

Fortunately all seems well now that I cleaned up the contacts in the little accessory fuse box that serves the pump. I had cleaned it early on, but clearly not well enough. The car seems totally reliable now.

I think my next step will be to try to revive one or both of the 3 port pumps that I now have on hand. Both work but are leaking around the power connector which I gather is a common problem. The Bosch rebuild shop that I talked to (and have used before for injection pump rebuilds) said it's a weak spot in the pumps design and said all they do is clean up around the connector and epoxy it to reseal it. It seems sketchy, but he said that's what they would do if I sent it to them and that I should save my money and do it myself. I figure I have very little to lose.

Other than leakage, there isn't much to go wrong with the pumps, and the o-rings on the pump body itself are easy to replace.

Worst case I can rig up an aftermarket pump, but I'd like to stay original if I can.