Need Help With 93 7.3NA

[PackRat239]

Hello,

I own a daily driver 93 F250 EC with the 7.3NA, 122,000 miles, 5 speed, 4x4, 33 x 12.50 x 16.5 tires, and it is giving me fits. I did change the filter a couple weeks after I bought it as a preventative measure. It usually starts great when cold, but recently it would not start when warm. Left me stranded. Thinking it was a fuel issue, I replaced the lift pump, bled everything and it started right up. Ran fine for a couple of weeks, then began making a lot of racket on start-up for a minute or so before it settled down and ran great. Now, it has begun intermittantly not starting warm , and running rough and loud for longer and longer before it smooths out. Maybe a minute or two tops. If I throttle up to about 1000rpm, it smoothes right out, but is noisy and rough under 800rpm or so until it smoothes out. Runs fine after it smoothes out. I drive it 25 miles each way every day. When it wont start, I put a rag dampened with gasoline in the snorkle of the air cleaner and it starts right up. Each time it wont start, it is warm weather, and warm engine, and the wait to start light doesnt light up. Has new fuel filter, Lift pump and quality return line kit with no visible leaks. Also, fuel milege seems to be suffering. Dont know if the injection pump needs rebuilt, or what. Any advice from the experts would be greatly appreciated. I am getting worried about going anywhere now and maybe getting stranded.

 

[S-west]

I'm no export but I just went through this and it was the injection pump. Luckily I had a spare.

 

[flareside_thun]

Sounds like it could be a combination of air intrusion as well as a bad injection pump. Do you have any noticeable fuel leaks? Look around the return lines and their caps, the fuel filter area and the fuel heater on the filter head. As for the pump, next time it gives you fits when it's hot try pouring some cool (room temperature) water over the injection pump. If it starts, youve found your problem. Over time, the interior of the injection pump wears and the tolerances aren't as tight as they need to be. Since heat makes metal expand, pouring cool water over the IP will shrink the housing and make the tolerances a little tighter. Welcome to the forum.

 

[icanfixall]

Welcome to the forum. So you just got the rig and really don't have a history on it. Good idea changing the fuel filter first off. Usually when a person changes the fuel filter we tell them to fill the filter with auto trans fluid. Then start the engine and run for about 3 minutes. That gets the trans fluid into all the injection pump areas that might be loaded with old fuel byproducts gumming it up. Next morning start and run like you stole it. If the truck is hard starting warm try pouring some cool water on the injection pump end where all the hard lines exit. This will shrink the pump. That causes the worn out pump to make more pumping pressure to start the engine. Also you can add some oil directly to the fuel tank in hopes of thickening up the diesel. This will work for a while but its time for a rebuilt pump.

 

[PackRat239]

Thanks for the replies. I did not notice any fuel leaks on the return lines , fuel lines or filter housing, but I have not checked the lines under the truck yet. I did not know the trans fluid in the filter trick at the time I changed the filter, but I will try that next time. I have been putting a quart of oil in the fuel each fill up, and that seems to help some. The last time the truck did not start, I did put a soda cup of tap water on the injector head, with no noticable difference, so I did the gas soaked rag to start it up. I have just priced out a pump, and ordered a new glow plug controller. This morning after the trip to work in about 70 degree weather, 25 miles, I had to run to town and the truck cranked for quite a while before starting and ran rough for 2 -3 minutes before settleing down and running well. I left her running while I was in the store because I did not want to take any chances with her not starting again.

 

[GOOSE]

The rough running after a warm start is tell tale of air intrusion. The last pump I had had heat soak problems but ran fine once started, no stumbling. Could you need new olives on the feed line to your injection pump? Also does this happen when a tank is below 1/4 full? My front tank needs some help with its pick up and presents these problems when approaching 1/8 tank to empty. Just a couple of things to look at, good luck.

 

[PackRat239]

Olives look ok with no leaks or seeping, and problem occurs with tank full or empty. Truck runs at all fuel tank levels. (so far).

 

[Shadetreemechanic]

For diagnostics, try replacing the return line that goes from the top of the pump back to the filter with a clear line. If the line drains when the engine is off you will know you have an intrusion problem and it will just be a matter of finding it. It sounds like air to me. When I have had worn ip pumps there was no rough running once I got it started. The roughness sounds like air working its way out of the lines.

 

[PackRat239]

Thanks, I will try that.

 

[PackRat239]

OK. I installed clear return lines last night as instructed. Truck was starting hard and running ruff again before I did. I ran it for a while and saw no bubbles, only clean solid fuel. I will look at it before I start it up this morning to see if the lines are still full.

PR

 

[93idisv2007]

i had these same problems it'll just keep getting worse try and poor a bottle of water on you inj pump when its hot and not wanting to start after i did that it started right up. if yours does its time for a new pump.

 

[PackRat239]

OK. Time for an update. After installing two clear return lines, and finding no air in the lines at any time, I have put several hundred miles on the truck in 90 to 100+ degree weather. Truck still starts great in the morning, and starts up ok thereafter, but seems to take longer with each start( still solid fuel in lines) and idles rough and noisy for longer after each start up. Last night I went to a friends for dinner, and when I went to leave after a couple of hours, ( high heat and humidity), truck would crank fine, but not start. Lines had NO air in them. I had to use the rag soaked in Gasoline again, and truck started right up but ran rough for a minute before smoothing out and running fine all the way home( 25 miles). It did have a slight, intermittent miss when I stopped to fuel up on the way home, and left her idling at the pump.

PR

 

[Shadetreemechanic]

Sounds like your ip is worn out. Have you tried pouring water on the pump when it doesn't start? I had a 94 for a while that always needed water to shrink the ip case when warm.
The other temporary solution to a worn ip is to thicken up the fuel. Add motor oil or veggie oil to the tank. It will likely take only a couple of gallons per tank to notice a difference in warm starting.

 

[PackRat239]

UPDATE: Today, the truck ran fine, started great, drove great, a pleasure to drive, UNTIL.... After running errands for a while, I stopped for lunch. When I went to leave, truck would not start. AGAIN. No air in lines. Cranks fine. Full tank of fuel. WTS light did not come on. AGAIN. Each time it has failed to start, the WTS light would NOT come on. Had to use gas on rag trick to start. Temp on gauge was below N, and air temp was around 75deg. Every time she refuses to start, I have not has a WTS light. It starts fine when the WTS light is on. I replaced the GP controller last week to eliminate that problem. I stopped and left her idling and did notice intermittent white exhaust, but she was idling smoothly.

HELP!!!

 

[Agnem]

OK, lets slow down here and recap. Truck exhibits symptoms of heat soak, and air intrusion.

Even though the OP said early on, that they tried the water trick, several people failed to see that and kept suggesting it.

Even though the OP said that the WTS light does NOT come on, not one person suggested a glow plugs issue.

Repeatedly the OP said the truck would start if a gas soaked rag was used.

OK, so far, everybody on this thread gets a zero! No soup for you!

BAD HELP guys.... c'mon... we are better than this. Let's help the man get his glow plugs fixed.


So, to the OP, Packrat... my appologies. Our minions are having an off day.

Please do not pour any more water on your pump.
Please do not put any more gas rags in your intake.

The next time you are having your problem, please do this.

Locate the glow plug controller on the back of your engine, and using a large flat bladed screw driver, with the ignition on, and an assistant handy, use the screwdriver to short the two large lugs of the glow plug controller contactor together for 10 seconds. This will manually provide current to your glow plugs. Attempt to start immediately afterwards, and report back.