Need some quick help please! 95 PS cranks but will not stay running

[Lockedhearts]

Quick back story. A couple of months ago I had it in the shop and had new batteries, alternator and wiring to alternator replaced. Got it back had a few times where check engine light would come on and truck would "lose power" , light went off it was fine. That seemingly resolved itself. Last week I went to crank to drive to work , it cranked, ran rough and then would not stay running. My current situation, my work is extremely busy through Christmas, this is my last free weekend , I need to go get hay for my horses. I have worked about 60 hours this week. Sensor , fuel filter? where to start?

 

[reptillikus]

Mine did the same, pulled the PCM out and found corrosion on two SCRs on the board. Had to replace it. Definitely worth checking.

 

[79jasper]

You need to find out why the check engine light is coming on.
I would say maybe icp sensor. Or UVCH.

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[Thewespaul]

Start by pulling codes

 

[IDIoit]

Start by pulling codes

^^ this! but not just pulling codes, you need to find the ICP numbers.
if you don't have a scanner, un plug the ICP. when doing this the ECU goes into a default.
see if it runs better

 

[79jasper]

Yup. You should notice a change in idle also.

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[clint bartels]

Also 1 super quick check is fuel volume/ pressure. If one or both is low or nonexistent poor starting/ running is usually the first symptom. If flow is found under cranking and or "running" your fuel system is "ok" with the potential exception of your filter (cheep insurance change it anyway). The 95 comes with a cam driven fuel pump that is notoriously awful.

This is straight from the Ford Motor Company FMC service manual

Fuel Supply System

The fuel system consists of the following three major subsystems:

• Fuel supply system
• Injection control pressure system
• Fuel injector assembly

The fuel transfer pump is a camshaft-driven, two-stage diaphragm/piston pump mounted in the engine "V".


Fuel is drawn from the fuel tank through the primary filter by the diaphragm section of the transfer pump. Pressurized fuel (approximately 28 kPa [ 4 psi]) is supplied to the secondary filter and returned to the second stage of the transfer pump. The piston-actuated second stage of the transfer pump supplies 276-345 kPa (40-50 psi) of fuel to the rear of each cylinder head where it flows to a fuel rail machined in each head.


Drillings in the cylinder head route the fuel to the plunger area of the fuel injector which can pressurize the fuel to 124,110 kPa (18,000 psi) for delivery to the combustion chamber via a conventional nozzle/valve tip arrangement.


Return fuel is plumbed from fittings at the front of each cylinder head to a junction block which contains a piston/spring type regulator valve that maintains pressure to approximately 414 kPa (60 psi). A de-aeration bleed orifice between the fuel filter and the regulator block vents air trapped in the fuel filter. Most of the fuel from the regulator is recirculated to the inlet of the piston (high pressure) stage of the transfer pump. Fuel return to the tank is limited to 30-38 liters (8-10 gallons) an hour through the use of a 0.0008mm (.020-inch) orifice. This prevents the fuel from overheating in the tank.

 

[79jasper]

That is incorrect. That sounds like for a 6.0.
7.3 only has one filter.
Tank -> low side of lift pump -> filter -> high side of pump -> heads to injectors -> back to the fpr on the filter -> tanks.


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[clint bartels]

That is incorrect. That sounds like for a 6.0.
7.3 only has one filter.
Tank -> low side of lift pump -> filter -> high side of pump -> heads to injectors -> back to the fpr on the filter -> tanks.


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First id like to say thanks for pointing out that I shorted my explanation. Upon rereading both my comments and the shop manual info I had to re-remember my thoughts and intentions on comments.

The other part of this is ford considers the water block portion of the filter a separate filter even though its really only 1. Some/ most aftermarket filters don't have a water block.

Attached is a pdf of the full fuel system info for an early build 7.3L PSD. Yes there are pictures

This setup returns relatively little to the tank(s) and keeps the fuel in a loop up at the engine. Fords thought at the time is to ease stress on the high side of the pump they would return the already pressured fuel to the pump. Unfortunately this design creates lots of temp in the fuel system towards the engine. And as a cam pump, pumps in relation to the rpm the excess fuel is relatively minimal. I have literally copied and pasted this from my online shop manual that as a tech at a ford stealership I have unlimited access to.

 

[79jasper]

Yup.
I went efuel, so mine will return quit a bit to the tank. Lol
I know before efuel, I had a return line between the head and regulator blow, talk about a massive fuel leak. Lol

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[clint bartels]

Yup.
I went efuel, so mine will return quit a bit to the tank. Lol
I know before efuel, I had a return line between the head and regulator blow, talk about a massive fuel leak. Lol

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Oh my what a mess not to mention the most expensive 20 miles you ever drove.

Yes in my opinion if your cam pump dies don't replace it update it. That is the time to go efuel.

 

[clint bartels]

But ill say this. Has our thread host found any issues on his truck? This is after all why we are here. Fuel or electrical is most likely or.... im assuming you checked your oil level. After all no/ low oil means poor running starting at best. I only mention this as it is one of the most over looked, no start poor running, repairs available.

 

[greenskeeper]

remove the oil cap and give a sniff...do you smell burnt wiring?

another test is to get the truck running and unplug the harness on each side of the engine one at a time:

1) no change in idle (you've found the bad harness)

2) engine stalls (you've found the working harness)