924Board.org

chris24 · Posted: Wed Sep 21, 2005 11:48 pm Post subject: fuel pump relay

hi
do they just stop working and never work again or do they become intermittent at the end of their life? if the car starts it keeps going, if it won't start then the fuel pump just will not kick in. three hours later its fine.
it's either an intermittent relay or a weaker electrical connection i think. i have ensured all the connections are good, but it is still a 50/50 chance that it starts. all other electrics are fine.
thanks
chris
_________________
1983 - 924 (185K miles) - not mint
1985 - 924 (148K miles) - mint
1990 - 944S2 cab (52K miles)

chris24 · Posted: Thu Sep 22, 2005 1:20 am Post subject:

I cleaned all the connectors i could find that have anything (and some with nothing) to do with the fuel pump and the car starts with both my fuel pump relays now...i hope its ok! I read a post that the relays can have a period of being intermittent before they finally die so i'll bear that in mind.
_________________
1983 - 924 (185K miles) - not mint
1985 - 924 (148K miles) - mint
1990 - 944S2 cab (52K miles)

Tigger937 · Posted: Thu Sep 22, 2005 2:39 am Post subject:

Chris, I recently went through a similar problem with my car and the problem turned out to be the intermittent relay as you described. I had 2 that acted this way. It turns out the relay becomes marginal as the circuit components age. I've come up with a modification that results in more stable operation and have since applied it to both relays without a hitch. I really didn't feel like paying $80 usd for a new one.
_________________
1981 931 (Concours)
1982 931 (Daily Driver)

"Think outside the box"

ATL_racer · Joined: 09 Aug 2005 Posts: 97 Location: Atlanta, GA USA

i bought a new relay for like 45bucks from napa, its the same one as the old vw rabbits have(i belive). it wasnt a big deal.
_________________
late 1979 porche 924, red 2.0l NA 5speed snailshell
Plans: Restore exterior, revitalize interior, install killer sound system, run engine in stock form and have fun.(+ a short throw shifter if i can find one)

Tigger937 · Posted: Thu Sep 22, 2005 2:49 am Post subject:

The 931 uses a different relay that has additional circuitry for rev limiting, overboost cutout, and a deadman throttle. Don't know if a 924 relay would work in a 931 (I've heard they do), but if it does, there would be loss of full functionality.
_________________
1981 931 (Concours)
1982 931 (Daily Driver)

"Think outside the box"

5150 · Posted: Thu Sep 22, 2005 4:29 am Post subject:

When mine went there were intermittant problems with the car dying, a faint burnt electrics smell inside the car for a while and then finally it died completely one day.
_________________
Mars Red '78 Euro 924 n/a
http://www.cardomain.com/id/5150_uk

Graphite? Grey Metallic '85 (late model) 944 2.5

There are two kinds of pedestrians: the quick and the dead.

D Hook · Joined: 02 Nov 2002 Posts: 3158 Location: Omaha, NE

Mine died once while idling in the drive way. I didn't know what happened. The car started right up about 5 minutes later so I attributed the problem to something else that I was doing on the electrics at the time. Then about a week later, it finally died for good pulling away from a stop light. Didn't have a spare then but now I think I've got an extra in the glove box. I've also had the AC relay blow, too.

While your driving, or right after you park the car, reach up and feel how hot those relays get up there in the fuse block. There's a great deal of heat generated up there. If you've had moisture in the cabin (as most of us have had), you may try unplugging and replugging the relays to get the corrosion worked off. Maybe some dialectic (sp?) grease would help. I've done all my relays that way and haven't had problems. (knock on wood.)

I've been thinking of mounting a 12v muffin fan up there to help cool things off.
_________________
'80 924 n/a SOLD

Tigger937 · Posted: Thu Sep 22, 2005 4:53 pm Post subject:

My fan relay gets really hot. I can hold my fingers on it for about 2 seconds max. I question whether this is normal. The relay contacts are rated 2X25 Amp, but if I remember correctly, the fans are fused at 16 amps each. I haven't had a chance to look at it yet, but it's definately next on my list. I want to pull the fuse/relay panel and get a look at the back side looking for any signs of corrosion or overheating.
_________________
1981 931 (Concours)
1982 931 (Daily Driver)

"Think outside the box"