newbie needs a hand.....

landsharks4 · 08-10-2010, 06:33 PM

hey all, just joined after spending several hours perusing your fine blog. I need to know if its possible i could get help with a problem i'm having trouble diagnosing. I have had trouble from time to time starting my 1987 928s4 (5-speed). Most times, when cold, it will fire right up, and when it does, it runs like a top. but once it doesn't catch the first time, chances are, its not starting at all. the most recent time this occurred, I figured I spent so much time cranking it over, it must be flooded. I pulled out a plug, BONE DRY. So I grounded a plug wire to check for spark, and found I had spark. So no fuel, right? I proceeded to swap out the fuel pump relay (only 3-4 months old) with a brand new one- crank it over- fired right up. Too easy? You bet! Came back to the car 1/2 hr. later, no luck starting again. I pulled out the brand new relay and jumped out the fuel pump as described in your blog. Even with the fuel pump running in jumped-out mode, it would not start. Pulled out the jumper wire (which, I gotta tell ya, I thought woulda worked) and put the newer of the two fuel pump relays back in. Cranked it over, started right up. let it run til warm, and shut her down. waited 5 minutes, cranked it up, and it started. shut it down, waited 35-40 minutes or so, and tried to start it again. This time, no luck. Its getting so tempermental, and I can't drive this car like this. I mean, i use it, but only to pull it out of the garage, flog it for a little while, and put it back in the garage. I would not dare shut this thing off, as it has stranded me too many times before doing EXACTLY the same thing. If its any help at all, once it does start, it runs like a top and pulls like a train. The battery and starter are brand new. Anyone have any ideas where I could start looking next? I am at a loss.

Mrmerlin · 08-10-2010, 06:55 PM

replace all of these relays with 53s
IV = ignition
XIV=starter
XV=EZK
XX= fuel pump
XXV= LH,

also replace the fuses or clean the ends with a pencil eraser, clean the ground strap and the 14 pin connector over the hot post

76FJ55 · 08-10-2010, 06:59 PM

have you tried replacing the EZK relay yet? if the EZK isn't getting power it will cause no spark and no fuel as it sends the PM signal to the LH computer. I know you said you had spark when you checked but that was right before it started back up so during the no start there may have been no spark.

landsharks4 · 08-10-2010, 07:01 PM

do you think these relays will cause the intermittent starting that I experience?? I'm just having trouble with the whole "sometimes they work, sometimes they don't" thing.
'

landsharks4 · 08-10-2010, 07:04 PM

SLOW DOWN guys, your waaaay ahead of me. Whats relay#15, the EZK? And thanks for the help!

76FJ55 · 08-10-2010, 07:10 PM

These relays are definitely a possibly. I actually just replaced my EKF (MY85 version of your EZK) relay for almost the exact same failure mode, only mine would occasionally shut down while driving as well.

76FJ55 · 08-10-2010, 07:12 PM

EZK is your ignition computer, and LH is your fuel computer, if that's what your asking.

Danglerb · 08-10-2010, 09:43 PM

#53 relays are cheap, just replace them all, save thinking for expensive parts.

Landseer · 08-10-2010, 10:05 PM

Clean all groundpoints.

Mrmerlin · 08-11-2010, 06:57 PM

Quote:

Originally Posted by Mrmerlin

replace all of these relays with 53s
IV = ignition
XIV=starter
XV=EZK
XX= fuel pump
XXV= LH,

also replace the fuses or clean the ends with a pencil eraser, clean the ground strap and the 14 pin connector over the hot post

Note when replacing the relays do one at a time,
so to figure out what one was causing the trouble

dcrasta · dcrasta's Garage

53's are pretty cheap. It is not a bad idea to replace them all if they are all original relays.

harborman · harborman's Garage

I replaced every 53 type. I removed every fuse cleaned every contact and sprayed panel with contact cleaner. Removed mainground strap cleaned body and strap connections real good.

Try doing all the above!

landsharks4 · 08-14-2010, 05:04 PM

got the monster up and running again today several times, it fires right up(ice cold, natch) But later in the day wanted to use it to pick up my son, and it was D.O.A. in the driveway. So I gave it a shot. I had a spare fuel pump relay, a "53" as you call 'em, and after some rolling of the dice, i decided to swap out #XXV (the LH relay). Which looked a little cooked, and i haven't even opened it up yet. the leads were mostly discolored, one being almost carbon black, another with traces of white (oxidation?). Popped the newish spare #53 in its place and bang, fires right up. So this is a thank you to all of you who helped get me looking in the right direction. I will continue on replacing the other #53's, and cleaning all the ground points. Just as soon as I stop driving...........and smiling. Thanks again fellas-I owe you a cold one!