Ford 7.3 n/a

[alt]

A friend of mine has a 1991 7. 3 n/a. He was telling me that his truck has been doggy lately he says that it seems that it does not have any power. Also that it is hard starting when it sits for a long period of time. It doesn't black stack. He changed the fuel filter. The engine oil doesn't seem like it has fuel in it. Does anyone have any suggestions on what I look for or what I should do. Where can I get a book on this engine for a low price? Thank you.



Paul

 

[Silver]

I used to tinker with those engines when I worked for U-Haul. (They all feel sluggish to me. ) The majority of problems we saw were with water in fuel (bad deisel) and air leaks in the rubber fuel hoses. I'm not a mechanic, so I won't try to pretend like I know what's wrong with it.

 

[Evan A. Beck]

Check the glowplugs, and make sure they are all working, and that the controller is keeping them on long enough. If the controller is bad, don't put a new one in. Install a momentary button to control the glow plugs. Its far more reliable, and easy to install. Check out the fuel line from the frame to the lift pump. The steel line likes to rub on the edge of the frame, just below the engine on the passenger side. A small hole in the line will cause air to be sucked in, resulting in hard starting after it has been sitting for a bit. Also, if the fuel return lines and fittings on the injectors are original, replace them! They will leak air too, and cause hard starting.

 

[dpuckett]

Like Silver, I am no expert, but have kept a few 6. 9/7. 3s going. Timing could have slipped, or just retarded internally. Check the return lines and o rings for leaks. DIS of Lubbock has good prices on kits. I imagin there are a few other places that can get a similar deal. I also talked to a guy that used to work for Ford, and he said the OEM pumps used a neoprene cam plate (similar to the old VEs on the CTDs) that would wear down, and not pump the pressure it should. Is there any white/ bluish smoke on acceleration? Or at idle? The rebuilt pumps use a steel plate, last longer, and are more reliable. Tell your friend good luck, and he needs to get a CTD to sink into it , though the 7. 3s are cheaper to get parts for.



Daniel

 

[drees1]

If over 80k on original injection pump, could need rebuilt. Like was said above get the steel timing advance sleeve pressed in it. It will last longer. To test the governor and general slopiness of the pump, grit your teeth and hold it wide open in neutral at high idle, 3800 rpm and see if it shakes and lays out a cloud of black smoke. A sure sign the old DB2 Stanadyne pump needs redone. Most fuel shops will have one rebuilt ready to go, exchange. Allow a couple or 3 hrs to swap it over, no problem to do. Remember to purge the air with the schrader valve on the filter head or it will never restart. International has a nice manual for about $35 - $40 bucks on just the engine. Easy to read and follow. If over 130,000 miles it would not hurt to replace the injectors, about $40 each. Those are good engines for about 300,000 miles, but the pump and injectors just don't hold up.

 

[dpuckett]

Originally posted by drees1

If over 130,000 miles it would not hurt to replace the injectors, about $40 each. Those are good engines for about 300,000 miles, but the pump and injectors just don't hold up.

Not quite aure about violating forum guidelines, but I know of a TDR advertiser that has NEW ones for $25 apiece. PM me for details. THe 84 we have is getting close to 130K, and I am looking at a fuel system in the near future. Uses a little oil, smokes, though not bad, and gets 17 or so mpg, down from 19 when we first got it. BTW- any idea on what to time a 84 6. 9 for high altitude? Everyone I talk to or thing I read tells from 4 ATDC to 8 BTDC. Quite a range.



Daniel

 

[bmoeller]

I thought it was DIS that had them that cheap?

 

[wrichards]

1991 n/a

I also have a 1991 N/A which has 75. ,000 on it. Tell your fried to go to TheDieselStop.com. It is the same as here just for free. Has a forum for the 7. 3 idi. I have had most of the common problems you speak of.



1) re Hard Start - Glow plugs need to be replaced with Motorcraft Beru plugs. There is a procedure that must be followed when removing them in case they have carbon build up. This build up can cause them to break off and fall into the cylinder and then you have a big problem. to check them you can use a test light but I found it best just to replace so you know what you got.



2) re Hard Start - glow plug controller mounted to the rear of the engine behind the intake may be bad. If glow plugs are all good wait to start light should stay on about 10 - 15 seconds depending on ambient temp, than cycle on and off for about a minute. If the controller is bad replace.



3) re Hard Start - you may have air in the system. Take a clear piece of plastic tubing and run it betweent the injection pump and the return lines after shutting down. next morning check for air bubbles. if found return lines must be replaced. Go to DIS for kit about $35. 00.



4) re Hard Start - the lift pump is also a suspect on these engines. If no air in clear hose, lift pump may be allowing fuel to return to trank and air to leak in. Many guys replace with electric pump mounted on frame rail.



5) Re loss of power - Injection pumps are usually suspect after 100,000 miles. These engines without turbos are very sluggish so question is how bad or noticable has it gotten. Guys have ran the injectors and pumps 250,000 plus without replacing. I would start by checking fuel filter and air filter. Other than that we may need more info, does it smoke, altitude, mileage etc.





I am also not a mechanic but have been through all of the above with my 7. 3 IDI feel free to pm if you have questions.

 

[dpuckett]

bmoeller,

You are thinking of the same place I was thinking; maybe they are sponsors? Anyway, go to the links, and click on them or go to www.dieselpage.com



Daniel