renn

a little background on my car. it's an RX7 with a stock 2001 LS1. cooling system is the stock F body radiator with a 4000 cfm Taurus fan.

A: car keeps blowing the fan relay fuse. it's a 40 amp fuse, i'm thinking about putting in a 50 amp to see if it still blows.

B: whenever the fuse blows and i don't know about it, when the car gets hot it starts to smoke A LOT. like diesel smoke. pretty sure this isn't anything other than gas, but not 100% sure. it looks greyish black. the car still runs fine, and pulls hard. the car never reaches the dangerous hot zone of the temp gauge... probably no more than 220.

for what its worth both times it's smoked like this when hot, have been starting after cresting a dip/bump in the road by my house. not sure if this has any effect.

i have taken the car to a reputable lsx shop and had them do compression and other tests and there is no problem with the motor that they could find. they rewired my fan relay but it keeps blowing.

i'm stumped on this one... any help or insight would be greatly appreciated!

RedHotG8

iTrader: (1)

Never swap to a fuse that's rated higher than the wiring, it can cause a fire. If the fuse keeps blowing there must be a short somewhere.

renn

any idea where the short might be? the fan comes on for a couple of days with the 40a fuse in there. then it just blows out of nowhere, can't figure out why.

all of the wiring in the relay was done by east coast supercharging. hesitant to think they'd wire something with a short in it.

RedHotG8

iTrader: (1)

If I were you I'd give them a call since they wired the fan.

renn

also just found this... this page seems to say that a 50a fuse is more appropriate than a 40a one.

http://www.thehollisterroadcompany.c...VIIIrelay.html


going to on monday

salemetro

iTrader: (5)

Yep....Taurus fan is an amp hog. IIRC, they can pull up to 60amps on startup.

RedHotG8

iTrader: (1)

It seems you found the problem. Try a 50 amp fuse and see if it holds up.

renn

still more concerned about the smoke out the back when it gets hot though...

fuel pressure is 60 psi running, 40 after its been shut off a few minutes

pcv or blowby? maybe o2 sensor?

RedHotG8

iTrader: (1)

I would get the fan fuse straightened out then see if the black smoke goes away. It's possible the O2 sensor is bad which will cause it to run rich.

remauto1187

iTrader: (1)

The fuse is there to protect the wiring ONLY! If the wire is sized for 40a then anything higher will likely allow a meltdown of the wiring and possibly a catastrophic fire.

If the bearing/bushing in the fans has gotten worn beyond its usable life (out of round) then the fan shaft will get shifted at an angle and cause excessive drag which will cause the electric motor to pull more current than what it was originally designed to pull. Then the fuse pops.

And ALL electric motors pull more current than what their FLA (Full load amp) rating is until they have spun up and are up to rated speed.

renn

i'm going to put in a 50a fuse and get the car nice and hot... and then pop the hood and watch it idle for 15 or 20 minutes and feel the wires and fuse. 16 ga should be enough wire for that fuse.

if it's abnormally hot or anything else i guess i'm going to have to rewire it.

remauto1187

iTrader: (1)

Scroll down to chart 2. 16ga aint gonna cut it unless your run is 3ft or less. If the wire in there feeding the fans is 16ga, it is probably melted and barely touching chassis ground now. I would go with the 14ga.
http://www.oemsurplus911.com/calterm/calwire.htm

renn

the fuse is less than a foot away from the rad and then another 6 inches or so to ground. right now all of the wiring is fine and the fuse is what was starting to melt.

it also might be 14ga, i eyeballed it.

remauto1187

iTrader: (1)

I would get a clamp on dc ammeter on that and see what it is pulling. That will tell all. If its really pulling some serious amps over 40 or so once the fan is up to speed and doesnt start to drop some then you got a fan tring to lock up on you.

How on earth do you miswire a relay anyway? Coil signal negative and positive. Contacts feed and load.

renn

i don't think the wiring is bad, but then again i wouldn't think as big of a shop as ecs would have wired my fan up with an inadequate fuse and gauge.

i work at a shop that does car audio installation... i can check the amps on the fan first thing in the morning.

renn

update: replaced the fuse this morning with another 40 and the fan comes on again and the CEL went away... but the wiring is definitely not enough for that fan so i'm rewiring the whole setup... thanks ECS.

renn

rewired the whole setup today with 10ga wiring and a bigger fuse and new relay. no problems yet.

also replaced the plugs with ngk tr55's gapped at .050.

i was told by the shop that the smoke could just be the ecu metering in more fuel when it gets real hot.

i'm also going to put in a catch can setup to help with blowby.

cadivette

iTrader: (1)

LSX tunes are set up to run richer as the temp gets real hot, usually 230 or higher. Richer runs cooler to help the chambers from getting overheated. If the fan is working properly now, it shouldn't ever reach the rich condition any longer.

renn

this is still happening.

i'm thinking it might be oil smoke now... happens during a long pull or usually right after a pull, but not on decel. pcv? blowby?

JS01

iTrader: (10)

Oil smoke isnt black. Put a wideband on the car and see what it's doing if you want to rule out fuel smoke.