6.5L TD 99 suburban would not start I replaced PMD and started and ran ok for a couple of days then just got worse now it starts and dies like lack of fuel,fuel gauge also not working but that has not worked long before the problem started need help as it is dangerous to drive as it just cuts out at any time.No check engine light coming on?

Tune up,cam sensor,crankshaft sensor.

before you do anything check you fuel line at the engine and see if you are getting fuel. sounds like its not getting any fuel.

You will cause the engine to go bad and have to replace if you keep driving,like a tooth ache,will get worst.

it sounds to me that #7 has a valve train problem, wiped cam to broken rocker arm,bent pushrod,broken spring,bent valve or burnt bad! Or it has broken ring on piston. shouldnt have kept driving,very bad idea. pull valve cover to check valve train. I would start there before going deeper into motor.

Hello Donn,

UN-fortunately 1988 is WELL before the OBD
(on board diagnostic)... DIAGNOSTIC TROUBLE
Codes (DTC) got standardized...

So DAYS can be wasted looking for commonality...
(troubles).

Rather than assuming your spark, timing, fuel, ECU...
Oxygen Sensors. INJECTORS are all askew...

I would suggest that if you SATURATED YOUR
HEADER BOLTS with LIQUID WRENCH...

and opened you EXHAUST ahead of your catalytic
converters... ahead of your mufflers... you engine would run...

Obviously DANGEROUS to operate in that condition... at
least you would know what had to be REPLACED before
you can operate your vehicle SAFELY.

If you decide the job is a bit too much... at least
check out your PURCHASE cost of a replacement
CAT and/or MUFFLER...

Try rockauto
http://www.rockauto.com/en/catalog/ford,1988,f-350,7.5l+460cid+v8,1126437,exhaust+&+emission

1988 FORD 350 7 5L 460cid V8 Catalytic Converter RockAuto

1988 FORD 350 7 5L 460cid V8 Muffler RockAuto

The switch just lifts off the rod from the lock cyinder after you unbolt it so not sure what it is you are doing here?

Found this online: GM Technical Service Bulletin #77-63-06Ab states that: "stalling, hard starting, and hesitation are symptoms of a failing PMD (Pump Mounted Driver) module." These symptoms usually (but not always) set a code 35 or 36 in the 1994 - 1995 models, or a code 1216 in the 1996 - up models. Often when this problem is diagnosed at a dealership or repair shop, the customer is told that the injection pump needs to be replaced. But in most cases, the PMD module can simply be replaced for a fraction of the price. The PMD module, (also referred to as the "Fuel Solonoid Driver") has been a major problem for Chevy / GMC 6.5L diesel owners since the introduction of the 6.5L electronically controlled DS4 fuel injection pump. It has been determined that heat is the primary cause of PMD failures. The PMD is mounted to the side of the fuel injection pump from the factory. But the injection pump does not provide adequate cooling to keep the PMD functional. Once the engine begins showing symptoms of hesitating, stalling and hard starting, the problem will only worsen with time. The problem only becomes more serious when considering the potential danger of your engine stalling in a situation such as pulling into heavy traffic or descending a steep hill and losing the use of power brakes and steering.

Hope this helps!

Take alternator off and have it load tested. Sounds like it's leaking.

spark plugs known problem when cold

you need a tune up new plugs wires and cap an rotor