924Board.org

[Dean47]

Fuel pump relay fuse blows when starting car if not right away shortly after starting when at idle. If it doesn't blow car runs fine until next morning it'll blow when starting starter has started to make grinding noise right after car starts it only grinds for about a second. Could starter going out cause fuse to blow? Fuel pump is fine so are all electric connects.

[!tom]

Starter has nothing to do with it.

The fuel flow is least while trying to start the car. I'm guessing there is a problem with the fuel return line or perhaps the FPR which is causing an excess restriction in flow.

Either that or your fuel pump is on the way out.

Are you using the correct rating fuse? Different years have different fuse requirements (as well as different numbers of fuel pumps).
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78 924 NA
5-lug

[Dean47]

My car is 1977.5 924 na 16 amp fuse on top fuel pump relay. Drove car today fuse didn't blow but got so hot couldnt touch it. Put in new fuse started car fuse got hot right away relay didn't relay stayed cool. Fuel pump stayed cool also all grounds are clean and tight any help?

[fiat22turbo]

Sounds like excess resistance in the circuit.

Clean and repair the grounds on the firewall behind the dash/fuse panel. Clean the contacts for the fuse, then move to the taillight panel and clean the grounds there.

Protect the connections with contact grease or Vaseline.

From there, if the problem persists then you may need to check the connections on the pump(s) and the relay connections on the relay panel.

The starter issue could be the ignition switch hanging up or an issue internal to the starter. Fix the pump issue first and then see if the starter issue continues.
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Stefan
1979 924 Carrera GTS (clone-ish)
1988 944 Turbo S (Silver Rose)

[Dean47]

Thanks I did that this summer when car came out of storage (9 years) but I didn't use contact grease. I'll go back and do it right this time and see what happens. Thanks

[!tom]

If the fuse is getting hot, then that's where the poor contact is.
_________________
78 924 NA
5-lug

[ideola]

In addition to what's mentioned above (about cleaning contacts and such), I would strongly recommend also cleaning the connections at the pump itself, as these are more exposed to the elements than anywhere else in the circuit. Clean the wire terminals as well as the contacts on the pump itself. If the protective rubber boots are torn or cracked, do your best to repair them with good quality electrical tape.

In addition, you should pull down the fuse block and carefully inspect the relay itself as well as the terminal ends where the relay plugs into the fuse block. Check the contacts where the relay's fuse is inserted, and check the spade terminals on the back of the relay. On the receptacle itself, check each of the individual wires that insert into the relay receptacle, as the tiny pins that hold the terminal ends in the receptacle can break or get flattened from repeated removal and insertion of the relay. This happened on one of my cars, and was the cause for intermittent failure of the pump circuit, and also caused the relay to get exceptionally hot. So make sure all of those terminals are firmly inserted into the receptacle. You can use a tiny jewelers screwdriver to depress the pin on each terminal end, remove it from the receptacle, clean it, then reposition the pin (CAREFUL! you don't want to break it off) so that it firmly reseats and retains the terminal in the receptacle.

There are a number of sources for moisture getting into the cabin and migrating along the underside of the dash (usually on the sheet metal) and then dripping onto the fuse block. Make sure all of the contacts on both the relay and the relay receptacle(s) are corrosion free and treat them to a liberal dose of dielectric grease. If you see any signs of corrosion or obvious water leaks, try to identify where it's coming from, otherwise, you'll be doing this job about every 6 months.

As Stefan suggested, be sure to clean both "ground crowns" that are above the fuse block. These are simply screwed in with a Phillips head machine screw, so you can remove them entirely for easier and more complete cleaning. Don't short cut this job. Get sandpaper, Emory boards, needle files, and a stiff wire brush (the size of a toothbrush), as these will all help the job go better.
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erstwhile owner of just about every 924 variant ever made

[Dean47]

Thanks for all the help. I started at the fuse cleaned contacts and fuse stays cool. I then went to grounds and fuel pump terminals and yes they where already corroded again. Doing it right this time. Thanks again you guys are a lot of help. [/list]