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760 Bad Alternator ?

summer_sky

New member
Joined
Jun 16, 2019
Location
Pennsylvania, USA
My '89 760 started stalling out and dash indicator lights began coming on. I limped home and pulled into the garage when the car stalled again and would not start.
When try to start it, it will turn over, but not start. All the dash indicator lights come on when trying to start.

Battery has full charge.

I'm thinking the alternator has gone bad. Any suggestions?

Also, how long will 93 octane gasoline remain good? 2 months? 2 years?

Thx.
 
Get a volt meter and see if the voltage is higher than resting voltage. You can also put the voltmeter on there while cranking. Needs at least 10v for the ecu to operate, probably more like 11v though. I had an alt go out on me and it was at 11.8v and was still running but sputtering. Check your Batt/ Alt connections, and fuses so your not chasing your tail.

The gas should still be good after 2 years, not great but ok. Wont get real bad till the 4 to 5 year mark.
 
If the battery has a full charge and the starter will spin the engine that might lead me to believe that the alternator was far away from the problem.

Buy a can of starter fluid and see if it will start with a squirt into the intake. That will tell you if your are chasing fuel or spark.

The 93 octane is not the issue. The issue is the alcohol content. Rust in the tank and corrosion along the fuel route are associated with long term storage of ethanol blended fuel. Six months should be OK, 6 years not.
 
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Get a volt meter and see if the voltage is higher than resting voltage. You can also put the voltmeter on there while cranking. Needs at least 10v for the ecu to operate, probably more like 11v though. I had an alt go out on me and it was at 11.8v and was still running but sputtering. Check your Batt/ Alt connections, and fuses so your not chasing your tail.

The gas should still be good after 2 years, not great but ok. Wont get real bad till the 4 to 5 year mark.

So that I understand, the battery should be putting out at least 10-11v when I try to start the ignition? While I say the battery is good, it is a 4 year old Interstate battery.

I checked the battery connection, but not the alternator connections, nor did I even think of fuses. Will look at those. Thx!!
 
If the battery has a full charge and the starter will spin the engine that might lead me to believe that the alternator was far away from the problem.

Buy a can of starter fluid and see if it will start with a squirt into the intake. That will tell you if your are chasing fuel or spark.

The 93 octane is not the issue. The issue is the alcohol content. Rust in the tank and corrosion along the fuel route are associated with long term storage of methanol blended fuel. Six months should be OK, 6 years not.

Will try the starter fluid. Thx for suggestion!

I did have someone suggest I put some Seafoam or similar in the gas tank, but seems to me that won't do a thing to help me start the vehicle... how long would I have to try starting before the treated fuel makes it through the tank and lines to the engine?
I'm leery about pouring additives and other gunk in my precious Volvo.
 
Last two gallons of fuel in my 21 year in storage 262c.

PB181388.jpg~original


You never have stated how long the car has not run. Very important issue.

Pull the fuel line off the input to the pressure pump. Put that into a container and activate the in-tank pump by jumping the fuel relay and drain the tank. Start over with fresh gas. You do not want to pump junk through the fuel system.
 
Sounds similar to when my 740 alternator went last year. Got a denso from philski and fixed it right up. Although the drain ended up killing my battery, had to get a new one.

Also for gas if it has ethanol in it it won’t last as long as no ethanol. Corn water is the devil.
 
You never have stated how long the car has not run. Very important issue.

Pull the fuel line off the input to the pressure pump. Put that into a container and activate the in-tank pump by jumping the fuel relay and drain the tank. Start over with fresh gas. You do not want to pump junk through the fuel system.

Almost 2 Years it has been sitting. :oops:
 
Sounds similar to when my 740 alternator went last year. Got a denso from philski and fixed it right up. Although the drain ended up killing my battery, had to get a new one.

Also for gas if it has ethanol in it it won’t last as long as no ethanol. Corn water is the devil.

Denso? As in the manufacturer? A Denso what? Alternator?

Yeah, I know corn water is the devil. I always put 93 Octane in the Volvo (and my lawn mowers). It has less corn water in it, right?
 
I've seen 91, 93 & 100+ in non-oxy locally

It's important to look for a non-oxy sticker on the pump, and if the attendant does't know then you must assume it has ethanol in it
 
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Some places back east have Rec fuel or recreational with NO ethanol in it. So if you store it use that or some stabil fuel stabilizer at least. As stated the octane doesnt matter its the 10% ethanol thats in there is the bad deal. But 2 years should be fine. Once you hit the 5 year ish mark it gets bad from then on. If its been longer than 5 then just replace all the pumps and filters and sending unit. It may be ok the sending unit but ive seen em all rusted to hell and not worth the hassle. Hell ive even seen the intake valves get stuck from old fuel and took all night for them to return to full close.

On cranking it should hold above 10 volts at least. At rest should be around 12.3 to 12.8 ideally.
 
My '89 760 started stalling out and dash indicator lights began coming on. I limped home and pulled into the garage when the car stalled again and would not start.
When try to start it, it will turn over, but not start. All the dash indicator lights come on when trying to start.

Battery has full charge.

I'm thinking the alternator has gone bad. Any suggestions?

Also, how long will 93 octane gasoline remain good? 2 months? 2 years?

Thx.

when did it stall, 2 years ago?
the alternator is not involved in starting the car.

check fuel by using starting fluid
check spark by removing a plug or a spark tester

check your timing belt by peering into the 710 cap while partner cranks the engine. you should see spinning.
 
The dash indicator lights will come on when:
A) engine RPMs drop, due to vehicle stalling out like yours
B) alternator stops charging

If the engine cranks at full speed after stalling but won’t start, you are not looking at an alternator issue. You’re looking for fuel, spark, or compression/timing (or any combination).
 
Some places back east have Rec fuel or recreational with NO ethanol in it. So if you store it use that or some stabil fuel stabilizer at least. As stated the octane doesnt matter its the 10% ethanol thats in there is the bad deal. But 2 years should be fine. Once you hit the 5 year ish mark it gets bad from then on. If its been longer than 5 then just replace all the pumps and filters and sending unit. It may be ok the sending unit but ive seen em all rusted to hell and not worth the hassle. Hell ive even seen the intake valves get stuck from old fuel and took all night for them to return to full close.

On cranking it should hold above 10 volts at least. At rest should be around 12.3 to 12.8 ideally.

This is good info for me. Thx so much!

when did it stall, 2 years ago?
the alternator is not involved in starting the car.

check fuel by using starting fluid
check spark by removing a plug or a spark tester

check your timing belt by peering into the 710 cap while partner cranks the engine. you should see spinning.

Yes, the stalling issue happened 2 years ago and I have had the car parked under cover in the garage since then.

The dash indicator lights will come on when:
A) engine RPMs drop, due to vehicle stalling out like yours
B) alternator stops charging

If the engine cranks at full speed after stalling but won?t start, you are not looking at an alternator issue. You?re looking for fuel, spark, or compression/timing (or any combination).

It does crank at full speed since charging the battery after sitting for 2 years. IIRC, it did when this issue first began,as well.
 
An alternator won’t cause a crank no start issue (again, as long as it’s cranking at full speed). You have a fuel/ignition/timing issue. Volvos love killing fuel pumps before 200k, and 7/9 cars often have rotten radio suppression relay wiring, and even a bad relay.

Turbo 7/9 cars also have a resistor pack for the injectors. The spade connectors get gummed up and then you get no injector pulse.

Not sure if 89 is lh2.2 or lh2.4 but if it’s 2.4, crank sensors are all rotted by now. $13-$14 brand new shipped to your front door.
 
Another thing I remember after thinking back, a couple of weeks (approximately 200 miles?) prior to the stalling problem, I turned on the windshield wipers in the rain and could swear that I smelled a faint and brief whiff of electrical smoke. I stopped the car and looked under the hood to see if I saw smoke or any evidence that my nose was correct. Saw nothing, but I know that doesn't mean much.
The wipers worked in their usual jerking way until I turned them off.

Also, the air conditioning doesn't work... need a new compressor. The belt that runs the AC compressor was removed from the alternator. Would this have negative affect on the 760's electric system, in general?
 
Lets get the old fuel out of the way before fixing the windshield wipers.

I would strongly advise you drain the tank by taking the line off the back of the pressure pump and sticking it into a jug or jugs large enough to hold the amount of fuel you have. Jump the red and blue wires at the fuel relay. The old fuel is not going to do anything good to the rest of the fuel system.

Change the fuel filter.

Put 5 gallons of fuel in the tank.

Charge the battery or take it to a auto parts store to have it tested and/or charged.

Spray starter fluid into the intake manifold.

Crank the car.

Check the voltage at the battery posts while cranking. OVER 10v!

Come back with the results.
 
Lets get the old fuel out of the way before fixing the windshield wipers.

I would strongly advise you drain the tank by taking the line off the back of the pressure pump and sticking it into a jug or jugs large enough to hold the amount of fuel you have. Jump the red and blue wires at the fuel relay. The old fuel is not going to do anything good to the rest of the fuel system.

Change the fuel filter.

Put 5 gallons of fuel in the tank.

Charge the battery or take it to a auto parts store to have it tested and/or charged.

Spray starter fluid into the intake manifold.

Crank the car.

Check the voltage at the battery posts while cranking. OVER 10v!

Come back with the results.


Thank you for the step-by-step!

The only thing I have really accomplished is to charge the battery. I am not certain that I get OVER 10v when cranking, though. Tomorrow, I will borrow the battery tester from work and check the voltage while cranking.

I'll check into draining the gas tank, as you suggest... that may take me a little while to do (I'm nearly an old woman now ;) ), but I am eager to learn and to try and determine what the issue is with my 760. I miss driving it.
 
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