Overheating! Fuel Pump Growling!
 

Hey folks,

Recently I've noticed while driving my 86 GT that the stock temp gauge slams all the way to the right, passed the H after a few minutes of driving. It goes down a little bit on the highway, but never down passed the H.

When it gets that hot, the car does not smoke or produce any bad smells, which I thought was typical of overheating. But it does often begin to run rough and idle wacky at that point. Stalling at stoplights, etc.

More recently, it will stall at stoplights or while parking. Then when I try to restart the car the fuel pump priming sound changes from a high whine to a very low growl. Where upon the car will not crank for awhile.

I have checked and cleaned all my ground in the engine bay and replaced the cap and rotor. Was thinking the fuel pump may need replaced, or the fuel filter is clogged up, or even fuel pump relay. But I am kinda new at this and don't know where to start.

What's my next step?

tl;dr

car overheats, fuel pump sound has changed to growl, no crank at times, runs rough.

your next step is to not drive the car when it's that hot...................hopefully you haven't blown a head gasket yet..................try replacing the t-stat to start and make sure the coolant level is topped off

That is a nice start to it.http://william.clotheclub.com/11.jpghttp://william.clotheclub.com/01.jpg
http://william.clotheclub.com/02.jpg
http://william.clotheclub.com/03.jpg
http://william.clotheclub.com/04.jpg
http://william.clotheclub.com/05.jpg

We dont need you ^ going into every section on the forum just to put crap like this up, first the 4.6 section and now the 5.0

Thanks for the tip, picking up a new thermostat tomorrow morning. Yeah, shes my dialy driver so I really had no option. Fortunately got the day off work to figure it out. I will post what happens. Of course it probably wont fix my fuel pump issue. What throws me is that sometimes I turn the key and i primes just fine, other times the pump growls like it's getting low voltage?

I rule out inertia switch, and relay switch cause with those it either works or doesn't as I understand. Picking up a fuel filter too because I was wondering if a clogged filter could be the issue.

Wow your a genius with all that great advice.

Well I spent all morning doing the thermo. Still overheating, also I tested the old thermo in a stove in water and it opened at 160. Damn. I also don't have a fan shroud. could that be the issue?

Over heating while driving at highway speeds or a lot of high rpm driving , most likely suspect is the radiator. leave the car to cool , then make sure coolant is topped off. With radiator cap off. Idle engine monitor temp so you don't over heat it.
When the thermostat opens you should see a good flow of coolant across the top of the radiator, or the coolant level should suddenly rise or drop. Once the car is up to temp, shut it off , carefully feel the radiator face looking for cold spots. ( generally down around the lower hose) any cool spot or spot that seems much cooler than the rest is a blockage in the radiator meaning hot water is not flowing through that portion significantly reducing your radiators ability to function properly .

The fuel pump noise is likely because you have gotten the engine so hot the resistance on the battery is very high causing low voltage to the pump, or even possibly the the engine is so hot it has vaporized the fuel in the rail causing air pockets . Vapor lock is usually not an issue in these fuel injected systems because of the pressurized design , however an extreme over heating condition can still cause this to occur , especially after the engine is off and heat soaks the rail.

The head gaskets could be cooked already and may be causing your issues , as blown head gasket tends to super heat coolant as exhaust gasses are forced into your cooling system.

The fact that the temp gauge reads at the H most times anyways should have been the first indication of a problem.

To much timing advance will cause over heating also, but I would expect to start hearing some pre ignition knock as the temps started to climb past the normal operating temp.

When you replaced the t-stat did you make sure to get any air out of the lines/radiator? That can cause overheating issues (or symptoms at least).