Fixed the 740...but headlights inop!

geronimo · 2007-03-18T00:02:59+00:00

It didn't run *not* because it was being flooded out by too much gas.The mechanic who had worked on it had the camshaft set so that with#1 piston a TDC, the rotor was on #3 sparkplug! I reinstalled the fuelrail, reset the camshaft timing, and it fired right up, runs fine! Also I found the real cause of what he was trying to fix byreplacing a $50 fuel pump relay.....the problem of it suddenly dyingintermittently. I looked the fuse panel over, and the fuse in #1position for the fuel pump power was totally shot! It overheatedsometime in the past...the plastic around the socket opening melted,the two fuse contacts were black and totally loosened. All it wouldtake is a bump and the fuel pump would shut down with the fuse thatloose. So that was an easy fix, I just broke out the bad/burned fusesocket and put a pigtail fuse holder in its place. Now the problem is that the low beam headlights do not work. Thehigh beams will work if you pull the stalk backward, but they do notlatch on, so they are only on as long as the stalk is held rearward. The mechanic was working on the fuse/relay panel when he replacedthe fuel pump relay. So I think it is something he induced. I noticedthat there is one relay base that has (I think) four wires going toit---identified as relay F in Haynes manual. The base is there, butthere is no relay. But Haynes manual says it is for front fog lightswhich the car doesn't have. So hopefully the Haynes manual is rightand that has nothing to do with the problem. There is a red round relay (A) which I believe is the bulb failuresense relay for the low beam lights. At least the Chilton 90-98 manualshows only the low beam lights powered through it. So this is apossible cause I guess. The Haynes manual says that relay K on thefront row is the central locking/main lighting relay.....maybe it isfeeding low beam power ? Unfortunately I don't have either relay.Advice?

Mar 18, 2007 21 Replies

Rate this thread:

Jon Robertson 19 years ago

Hi there if the fuel pump fuse is blown your pump in the tank has gone causing your main pump to work over time and over heat .My wifes car did the same thing .You wont notice much till your low on fuel then it goes haywire as the small in tank pump cant deliver to the main pump.Simple job but a real problem for a non volvo mechanic to figure out .

Vote

James Sweet 19 years ago

The main pump can fail in this way even if the in-tank pump is good. The one on a friend's 240 did several years ago, it was pulling so much current the relay socket melted down.

Vote

Join the Discussion

Have something to add? Share your thoughts — no account required.

Didn't find your answer?

Ask the community — no account required