I have a slightly unusual problem I think. When I get in it to go to school in the morning the turn signals don't work and the heater won’t turn on. Then in the afternoon, after school they both work, turn signals, climate control, all that good stuff. Anyway does anybody have any idea why? Also it's getting really bad gas mileage, like 10 mpg. Is there anything obvious that would cause that? Thanks.

 

Is it temperature related? ie after school has the car been sitting out in the sun and got warm ? If so it could be an electrical connection thats not making contact when everything is cold.

10MPG.... what engine/year is the car ? (It's useful to add this info into your signature so people don't have to ask you) and are you in the US or UK/Europe as the definition of gallon is different. I get around 11MPG from my US '92 V12, mainly due to the fact I drive it mostly in town, stop/start kind of thing. It will return 16/17MPG on a run though

 

The best place to start with weird electrical problems is with the connectors to whatever components are acting up.

Quote:

Also it's getting really bad gas mileage, like 10 mpg. Is there anything obvious that would cause that? Thanks.

What year and engine?

Are you getting black exhaust smoke? Are the spark plugs black? Any other running problems?

Cheers
DD

 

Sorry, it's a 1983 xjs v12 and I'm in the US. As for the mpg that was on a long trip going 55mph the whole way. It put's out some white smoke at startup but there’s no black smoke and it doesn't last long. I just changed the spark plugs before I started driving it and as far as I know it doesn’t have any other running problems. I'll check some connections and see if I can park in the garage tonight.

Thanks.

 

Some things to look for on the fuel economy problem:

- Distributor mechanical advance seized up
- Distributor vacuum advance cannister inoperative
- Incorrect base timing
- Fuel enrichment switches staying on
- Incorrect fuel pressure
- Leaking fuel pressure regulator
- Faulty coolant temp sensor

If you want details on any of the above, post back !


Cheers
DD

 

Your relays are 20 years old. The weird electrical behaviors sound like goofy relays to my ear but I don't know your 82's electrical plan at all.

One sneaky way to suss out bad relays is move the buggers around in the car. You're going to find that there's more than one of each on the car for the most part. The problem will follow the relay and that'll help you figure out which one is being intermittently irritating.

Edited to add: CHECK THE PART NUMBER. Make sure when you move the relays that they are in fact the same part. There's a couple of different kinds and they don't mix and match.