I've been suffering a strange problem ever since I've had my timing advanced. Before bumping the timing, the truck would start with a "blip" of the throttle and maybe a half rotation of the motor. Now, the motor cranks over several rotations before it fires. If I give it throttle like I used to, I'm rewarded with a black/grey cloud on startup. If the truck is warm, it starts just like it used to. Don't get me wrong, I love the top end power the timing advance gave me, but I was under the impression that advancing the timing would give me easier startups. Also, I'm not noticing the fuel mileage increase everyone talks about. I'm getting about 15 MPG, empty, with a light foot. (most of my driving is between 30-55 mph, I very seldom get a chance to really open her up on the highway). The truck just turned 100,000 miles, with a fairly new O/F valve and fuel filter. Soooo, what do you guys think is causing this issue? Am I looking at replacing the dreaded supply and return lines? Any other issues anyone can think of? Thanks for any help you guys can offer!

MIke

 

Mike:
Check the pre-heater filter Pre-Filter Cleaning . Sometimes it is gunked up. How old is your airfilter. It may not be a clean as you think. Sometimes the mileage isn't as spectacular as you would think. I know with the price of fuel we're all trying to squeeze every last drop out that we can. You should also run some fuel additive such as powerservice to each tank. It will help keep things clean and can boost fuel mileage. Your "35 -55 mph, can't really open her up" driving isn't helping either. You may be building up some carbon in the cylinders. I think it's good to every so often go for a good spin . As for the slower starting, try increasing your idle rpm up. Mine has done that as well. Or, you can just hold the skinny pedal down slightly when starting.

Paul

 

My bet is your timing is set higher than you think it is, most likely over 20°.

 

Does your idle need bumped? I did all that fuel line, tank module ect last winter and timing ended up being my problem. I had hard starting like losing prime, some white smoke and lower fuel mileage. Also egt's were increased and smoke had a grey haze to it. PM me if you need a second set of eyes to help look at it.

 

Well something else must be to blame, I just got my timing advanced and it starts easier. I can't say I've noticed any improvement in mileage but I've only ran a half tank so far so no conclusions have really been made yet.

 

I was at 19 for a time before I straightened out my CPL oddities and though it didn't light in half a crank, it would still come to life within 2....no pedal help......and in the winter as well. Now with the 370's, a little go pedal is mandatory or it'll crank and crank

Hey infidel, didn't someone mention in a distant post about the possibility of an O/F vlave causing an airlock momentarily 'till FP came up? I thought I saw you in that one.....just another possible coincidental occurance faking you out into thinking it is related to the timing maybe.

 

Thanks for the replys fellas. I did have to raise my idle when I got the truck back from the shop that did the timing. I'll look into cleaning the pre filter as well. To be honest, I've never cleaned it since I've owned the truck and I know darn well the previous owner didn't have it cleaned either. My air filter is getting some age to it, I should probably look into replacing it as well. Infidel has me scared with his timing statement. The shop that advanced the timing (who has a very good reputation around these parts) would not give me a number on what he advanced it to. He said that it had slipped a little over time and that he "knew where to set it." I can't imagine he would set it over 20 degrees, but crazier things have happened. I'll keep everyone posted when I get a chance to take a good look at it. Thanks again.

MIke

 

You need to know how far the timing has been advanced before you bother to look elsewhere for the problem.......it is more than a coincedence that the truck happened to not start as well right after the timing was advanced.....how was it advanced? Was it advanced by precisely measuring the plunger depth on the pump or did they just wing it and do it by "feel"? I agree with Infidel, more often than not when someone attempts to advance the timing without measuring the plunger depth, they advance the timing far too much. Go back to the shop and ask how it was timed....if they measured the plunger depth they will know exactly what it was timed at......if not, I expect you will get a somewhat vague answer. FWIW, much advance over 20* makes for a difficult to start CTD.

 

Wouldn't tell you where he set it , you did pay for this service, right? If he wouldn't tell you, it's probably because he couldn't tell you cause he didn't do it right. Using the correct tools, you know where it is set at EXACTLY!

 

The shop that set my timing has the best reputation around for making power with diesel trucks, so when he didn't tell me where he set it, I didn't worry too much about it. The tech that did the work has a very fast 12v truck and I was having such a difficult time finding someone to set it, I was just happy to find someone to do it. I assume he was thinking I was an "internet mechanic" and didn't know what I was talking about (which I really don't when it comes to timing a diesel truck)
After the truck is warm, it fires right up like it used to. Does this sound like the timing is advanced too far? Wouldn't the truck need a little "help" every time I started it or am I wrong? Anyone know of any good diesel shops in the MD/PA area? My biggest concern is that I'm going to damage my motor running it this way. If I get a chance tomorrow I'm going to give these guys a call and see if they can tell me where they set it. Thanks again.

 

If it's as high as Bill suggested your a good candidate for a head gasket replacement in the near future.

 

Mike, hate to say it but your symptoms are classic 20° plus timing.
There is a tendency for engines with over advanced timing to blow head gaskets but if yours was that advanced you would have a much harder time starting it than you describe. Racers and sled pullers will sometimes approach 30, but they blow head gaskets.
Your mechanic may be very good at setting the timing by feel but unless he knew where it was set before he started could have gone way beyond the 16° or so that would be ideal for your truck.

 

Sounds like timing to me. If you dont measure plunger depth you cant be presise. Were i work we get this once a week. They get some back lot mechanic to set the timing, but they set timming well over 19 degrees.

 

An easy way to get a ballpark is look at your IP. if the timing marks on the pump(where mounting shoulder is) are higher than 1/8 of an inch, then chances are its too high. as mentioned above the plunger method is the correct way, but atleast you can get a feel for where its at on your own. Usually...Usually 1/8" higher gives about 15.5 to 16 deg, but i would only use that method to see if they did just "wing" it, not to attempt to set on your own.

 

Isn't that only on the first gen VE pumped trucks? I thought the P7100s were timed using a different method?