When I first start the car, the amp gauge reads very low and the car seems to struggle for about 5-10 seconds, then it runs fine. Is this an alternator or battery issue?

The car wouldn't stay running recently, but I replaced the spark plugs and fuel pressure regulator hose and it runs well after that. I've also replaced the in tank fuel pump.

How hard is it to replace the fuel filter?

Also, the car seems to have a hum too it about 15 mph, is this an axle/bearing issue?

Thanks!

 

When the volt gauge is reading low at start up, blip the throttle over 1500 and see if volts come up. If so, the excitor circuit is bad in the alternator or the wire has come loose on the back of the alternator. Really doesn't hurt anything. The engine will run at a lower rpm because it is running off the battery instead of the alternator until the revs go up and the alternator kicks in. If it's unrelated to rpm's then you may have a bad diode in the alternator or the regulator is going out.
The fuel filter is beside the inline fuel pump under the car. Not terribly difficult to swap out at all.
The hum is impossible to diagnose over the internet. It could be something loose under the car or hood, exhaust rattle, transmission going out, carrier bearing, wheel bearings, u-joints, transmission input or output bearings...and the list goes on. Or...maybe it's happy!

 

Thanks for your response.

I put a multimeter on the battery and that is what occurs, when I rev the engine, the volts go up, but as soon as I let it idle back down, the battery begins to lose voltage. I am trying to determine if this is an alternator issue, regulator or battery. I have a new battery on the charger and am going to put that in this afternoon, if this problem continues, I plan on replacing the regulator then alternator if needed. What do you think?

Thanks!

 

I think it would help if you tested the alternator independently of the battery. Do this by putting the + lead of the multi-meter to the large output of the alternator and the negative to chassis ground. Do not touch anything w/ the + lead except the output terminal of the alternator or fireworks will ensue. Your 90 has an internal regulator; it's seldom worth the trouble to replace as entire alternators are so plentiful. Assuming your volt readings never went below 12.5 to 13, it's a safe bet it is the alternator. Putting a good hot battery in will eliminate the symptoms for a bit until it is depleted.

 

I had the alternator tested (while in car) and was told it was fine. I replaced the battery and while doing so noticed a plug on the fender next to the battery was unplugged. (A capacitor perhaps?) Now the car runs fine at idle and highway speeds and the volt meter on the dash doesn't jump all over, also, testing the battery with the multimeter, it holds at 13.75 whereas the old battery would drain, especially when i turned on the blower motor, lights etc...

So i hope between the new battery and the plug on the fender, it will keep running well, I'll monitor the battery every few days w the multimeter.

Now though! I notice the car won't downshift when I get on the throttle, it will go back down through the gears when coasting to a stoplight, but the "passing gear" doesn't feel like it's there... I checked the trans fluid and it was full and didn't smell burned... any ideas on this one? perhaps a solenoid or plug somewhere?

Thanks much!