A friend of mine has a 93 and 94. Both trucks are stock. Having trouble with the 94 having a high rpm miss and low on power. Doesn't have the power the 93 does. The strange thing is this truck will rev to 2800 rpm and I checked the seal on the gov spring cover and it is there, so I don't think anything has been modified. The miss is coming in only at 2700 - 2800 rpms and when it starts missing there is some blueish smoke from the exhaust, not black. I'm not sure where to start. I think I would check timing first, but I don't have the timing tools. Could it be floating a valve, bad injector, Maybe a problem in the afc control, could the fuel lines be porus and pulling air, I've had that problem with my semi trucks before and it was hard to find the trouble because no fuel leaks. I did put in a new overflow valve, it had never been replaced and at 240,000 miles I figured it should be replaced anyway, didn't help. I am trying to do the cheap, and easy things first to find the problem. I have arthritis bad and don't even want to think about replacing the fuel lines so may have to take it somewhere to have that done. I wish the miss was at idle, I have a temperature gun I could shoot the exhaust with. I can't help but wonder if the low power and miss aren't related. If anybody can think of anything I am missing I would appreciate help.
Thanks!!!

 

A couple of things come to mind and it sounds like you are on the right track.

The fuel lines are suspect. A fairly common problem. Probably needs replacing. Maybe sucking air during high demand/revs. Cheap enough to do, just a witch to get at. Especially with your physical limitation. It is a real acrobatic feat to get them puppies changed out.

Infidel kind of eliminated the access problem by running rubber line all the way back to fuel tank, then up to the front away from the tranny and engine. Sounds like it is much easier to get at using his method. Even if you just ran the rubber line down to and easy to access spot along the fram rails and connect the rubber fuel line at that point. Perhaps he can/will coment on that. Still wouldn't be all that expensive.

I wondering about timing as well. It can be done relatively cheaply. Harbor frieght has a dial gauge for about $10.00 and a magnetic stand for about $15.00. You also need the delivery valve socket (it's a must) and it runs about $40.00 from snap on or miller. Thats about it for the "specialty" tools. Yes the specific timing tools from snap on and miller is better, but it can be done using a dial gauge. The problem is the process, and once again can be kind of physically challenging because of the need to rotate the engine multiple times to find TDC, marking the flywheel, then turning the engine again to check the timing.

I think having the timing checked by a shop would be money well spent AFTER you have checked the obvious and done things like the fuel lines, check and adjusted the valves, filters, prescreen filter (is a commonly ignored item), and checking for turbo leaks, but it does not sound like a turbo problem. The afc control is one of the last things I would check, especially if there is no indication of someone messing with it.

Check out www.dodgeram.org they have tons of "how to info" so you can decide what to tackle and what not to. Good luck, hope this helps, Kevin

 

I would suspect low fuel pressure caused by a bad overflow valve or plugged filters.
Check the filter in the fuel heater, instructions here http://dodgeram.org/tech/dsl/filter/pre-filt_clean.htm

If you don't have the means to check the fuel pressure just replace the overflow valve
best price by far here

Precision Diesel Injection and Turbo Inc.
Marty Tompkins
888-734-7349
$30 + $7 shipping and handling.

 

kd460, sounds like you are thinking like me. The fuel lines was one of the first things I thought of. He is going to bring it over Tuesday and I think the first thing I will do is check the preheater and then get the fuel lines changed. Then if that doesn't do it I will check the timing. I do have a metric dial indicator and could make an adaptor for it. I also made a blueprint once of a barring tool and as I have a machine shop I can make that. I will just have to get somebody to help me with that timing pin. I just can't help but think it is running out of fuel because when it smokes while missing the smoke isn't black, just a haze. Thanks for your good reply.
Michael

 

infidel, I was thinking like you and that was the first thing I did. I removed the spring and it only measured about .350 in lenght. I thought for sure that was the problem but it still missed after I put in a new overflow valve. I measured the new spring and it was only about .400, I thought I read somewhere they were supposed to be .500, but the new one wasn't. Thanks for the reply!!
Michael

 

Milkman, if you have machine shop than an adapter for the indicator should be easy as well.

Heres a tip just between you and I , the stock oil drain plug is the same thread size and pitch as the delivery valve holder. It threads in like it was made for it. I drilled out the center of mine (after I got a new one) lengthwise. The hole is just a touch larger in size than my dial gauge, then drilled a hole sideways(and tapped it) for a set crew to hold the dial gauge in place. WALA! Instant dial gauge holder for the cost of an oil drain plug. On my set up, there is no need for the extension that comes with the miller or snap on tools. I do believe I used a washer to take up a little space, but a slick cheap and easy way to get around the cost of the miller or snap on. Sorry, forgot to mention, the engine can be turned backwards easily by using a 7/8 inch socket on the alternator nut. Forwards and it will slip. I made a gizmo bracket that bolts up to the crank balancer bolts so I can turn it the "correct way" with a ratchet. To my surprise it works in both directions. Looks crude, but it works.

If needed I can send you a pic or two. Replacement oil drain plugs can be purchased here: http://www.cgenterprises.com/

They have all kinds of drain plugs, washers, magnetic plugs, you name it he's got it. Fast service, nice guy to deal with. Pick up a couple of the nylon washers for the drain plug, and get a magnetic one to replace the old one. The nylon washers solve the common oil drip problem as well.

Good advice on the overflow, and sorry I missed that one. Glad you checked that out. Just eliminates one of the possibilities.

BTW, hopefully you found the timing instructions, prescreen/fuel heater info on that link that I (and infidel) provided you. Have you addressed the killer dowel in issue?

So you own a machine shop eh?? Where are you located? Be careful we may put you to work. I can think of a few things all by myself Good luck, keep us posted, Kevin

 

I agree with the above posts. The main causes for the high rpm miss are late timing, or low fuel pressure. I usually set the timing to 14 degrees with a light, that relates to about 16 degrees with a dial indicator.

 

kd460, wow, you will never know how much I appreciate the tip about the oil drain plug. I just remembered I can't turn metric threads with my lathe so that will be handy. I understand the rest of your instructions though and can handle that. Really glad to know the tip and thanks! I knew I could turn the engine one direction, I need to study the balancer and see what I can do with that. If you already have the photos I would like to see them but don't go to the trouble of crawling under your truck to get them. Yes, I understand the links and thanks to you both for posting them. I also have fixed my dowel pin a long time ago. I bought my truck new in 94 and have been playing around with it for years so have had a chance to learn some things about it. It is running 370's, 8 fuel plate. 191? delivery valves, 3,000 gov spring kit, 16 exhaust housing, Southbend clutch and I think that is it. I have loved my truck since day one and it is still almost like new. I live in Az and have taken in machine work I found on the internet so don't hesitate to talk to me about anything you may need made. Here is something I made last week for one of my machines, a crank handle and clutch from stainless steel. New here so don't know if I can post a photo or not. Looks better in person.
http://myweb.cableone.net/michaelaz/crank.jpg

 

torquefan, I sure can't argue with that and looks like I'm going to find out which it is. If you have time would you explain how to time with a light. Thats another new one on me. Is it a reliable method of timing our trucks?
Thanks
Michael

 

OK, I just tried to look for my fancy hand made crank turner thingy, it's in never never land for the time being. I'll find it when I'm looking for something else.

Anyways, it's basically a peice of 1/8' steel cut in a circle, and drilled in the same bolt pattern as the crank balancer hold down bolts. An old deep well socket is welded in the middle so the part that connects to the ratchet is facing towards the front of the truck and the end that a bolt would normally fit into is the part that is welded to the flat plate. The holes that the crank balancer bolts go into are slightly elongated and slightly oversized just to make it fit a little easier. The only drawback is the need to remove the balancer bolts in order to install, but hey it works.

Can't remember the size of the socket, but was a deep well, I think it was an old 5/8" spark plug socket. It can't be to big or the bolts for the balancer will hit (or the socket used to install the bolts).

It is kind of tight with the fan and the shroud in there. Some people have been able to pop the gear with all that stuff in place, I just find it an easier job with it all removed, even if it takes more time. It saves the hands.

BTW, you do need a (30mm I think) socket for the nut on the pump gear, and make sure you use a magnet and a rag stuffed under it so you don't drop that baby into the engine.

The pump shaft and mating surface on the gear gets sprayed down (this is critical) with brake clean or some other non residue cleaner before reinstalling. If any oil is left on this, the gear can slip. I used a harmonic balancer puller to pop the sprocket.

This is just a few of the things I remember. Not sure how much of this stuff you already know, so don't want to be redundant. Hope thishelps, Kevin

 

Another point to check is pop test your injectors. You may have one with low opening pressure and causing needle bounce at high rpm's.

 

Lots of pros use a light to check the timing. Don't understand why it would be a couple degrees off from the dial indicator method though, always been spot on the same for me.
You can use a regular timing light with an adaptor that clamps over an injection line or a light specially made for diesels, neither is cheap. They sense the pulsations of the injector line.
The dampener is wrapped with graduated timing tape especially made for the diameter of the dampener you are working with and TDC marked. The rest of the process is the same as checking the timing on a gasser.
The light method is a fast way to check timing especially if TDC is marked but doesn't make it any faster to change the timing, the dial indicator method works better for changes.

 

i khnow when my old ford's timing was slow, you could floor it and it popped and sputtered and blew white-gray smoke. re-timed it by ear."easy to do on ford, almost impossible on dodge" and problem solved. if it was a fuel leak, seems like it would be very hard to start.

 

Thanks Bill and Banks. I wish I had one of those for checking the timing but guess I will use the indicator method.
Michael

 

Regarding the two degree difference with the light, I was told years ago by the tech who introduced me to the light that there was a 2 deg. difference between timing at the pump and at the injector. I just assumed it related to the time taken for the pressure to build enough to open the injector. I had never actually verified that but did notice that on all the low mileage trucks that I put the light on, the timing would read 2 degrees later than what the truck called for on the data plate.
I think maybe I'll check some with both the light and dial indicator now.