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Discussion Starter · #1 ·
Hello every one. Sorry if this ends up in the wrong place, or it’s been posted before. I have a basically stock 97 12 valve that I cannot figure out. Couple weeks ago it started struggling to get up some hills with my truck bed camper on. I didn’t notice it before, but now it’s getting annoying when the mini van soccer mom mean mugs when she passes me. The truck seems to do fine on flat but I end up shifting between 4th and 5th pulling the hills. Just won’t hold the boost in 5th and 4th runs out. Replaced waste gate,fuel filter, cleaned pre screen, new afc hose, torktek overflow valve. And checked fuel pressure 20ish at idle 32 at 2500rpm. No boost leaks that I can find. and no air in fuel. Other then dropping the tank and checking for blockage I don’t know what to do.
 

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Welcome! What are the RPMs in 5th gear, and what is the boost psi when going up the grade? Also, it would helpful if you could fill out your signature with relevant truck information such as configuration, any upgrades, tire size, ring and pinion, etc.
 

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Discussion Starter · #3 ·
Welcome! What are the RPMs in 5th gear, and what is the boost psi when going up the grade? Also, it would helpful if you could fill out your signature with relevant truck information such as configuration, any upgrades, tire size, ring and pinion, etc.
will update that stuff. Thanks! Rpms in 5th will be around 2250 an will drop off to 1500 if I let it go before shifting. Boost is about 20 but drops with the rpm and it seems to do it quickly. Truck is a 5 speed basically stock with torktek overflow valve and Napa bhf filter. Sitting on 35x12.5 with a 4” lift. Ring and pinion is 355 I think! I’d have too check it again.
 

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Have you checked your FSS for full travel? It is common for the boot to deteriorate and jam the linkage in the partly open position. Enough to run but not enough to climb hills.
 
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Discussion Starter · #5 ·
I have stuck my hand under there and felt the boot. It’s all intact an seems ok. Is there a way a guy could delete it to test if it is bad.
 

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Did you push on the lever to see if it will move upwards farther? I had a similar problem while pulling a trailer, no power while climbing hills. In my case the FSS rod had disconnected from the plunger and the only thing holding them together was the boot. This was the "temporary" fix I made in a parking lot about 400 miles from home. I discarded the boot and drove without one for about a year.

928969
 

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Discussion Starter · #7 ·
When the truck was running I tried pulling up on the lever and it wouldn’t move any farther. When lever goes up the boot almost feels like a balloon is that normal?
 

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That sounds normal. However, I believe it might be a good idea to remove the FSS from the truck to check for binding. Then clean the plunger and bore, maybe a little dry lube. Also check the lever itself to see that it isn't spinning on it's shaft. There is a woodruff key that could be sheared. It only costs time and would either confirm or eliminate the FSS.
 

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Over the weekend my truck acted like it was low on power so when I got home I checked and found out my pull cable for the FSS had moved and wasn't pulling the arm all the way up. Haven't had time to drive it since but i'm sure it'll be back to running like it should.
 

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Discussion Starter · #11 ·
That sounds normal. However, I believe it might be a good idea to remove the FSS from the truck to check for binding. Then clean the plunger and bore, maybe a little dry lube. Also check the lever itself to see that it isn't spinning on it's shaft. There is a woodruff key that could be sheared. It only costs time and would either confirm or eliminate the FSS.
Checked the FSS tonight. Every thing seemed to be in good order. Put a new air filter in it an took it for a drive. It helped but didn’t blow my skirt up like I’d like. Pulled the hill in 5th but was lugging by the time I got to the top. Boost held around 17 after dropping from 24. The lift pump seems to be making almost a sucking noise but when I checked fuel psi I also checked for air leaks and didn’t see any. Am I expecting too much for being stock?
 

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At what RPM were you at the top of the hill while in 5th gear?

I don't understand the fascination people have with the air leak theory. If there is a leak prior to the lift pump the result is difficulty in starting or no start. If the system leaks after the pump there is fuel coming out of the leak. If the engine starts easily there isn't an air leak problem. Pretty simple.

With the fuel pressures you reported you do not have a lift pump problem. BTW, it does suck fuel but if you can hear it over the engine clatter I envy your hearing capability.
 

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Discussion Starter · #13 ·
Thanks, the heating sure comes in handy during hunting season. The rpms I want to say were around 1600. I’ve been thinking about the past couple trips iv made. When I fuel up after a trip I notice a lot of vacuum in my fuel tank when I take the cap off, could this be making the lift pump work overtime during a load? I’m going to take the truck for a run tonight with the cap off and see if that helps.
 

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The tank pressure is normal. Mine has done that since new. You can't "overwork" the lift pump. I predict there will be zero difference with the fuel cap removed.

If you were down to about 1600 rpm it explains why you weren't making any more boost. Lugging is when you mash the pedal and do not accelerate. If you can't accelerate you won't produce increased boost. I suggest you try it again above 1800 rpm, 2000 is better. The engine shouldn't be lugging at those RPM. If that rpm causes you to be speeding then shift down. EZ-PZ
 
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Discussion Starter · #15 ·
Took it for a run tonight. Seemed to run ok I think. Fuel cap off didn’t seem to make a noticeable difference. In 5th the truck was doing 75 at about 2250 rpm and boost at 22. As I was climbing the hill I slowly watched rpm and boost dropping, so I floored it. Didn’t pick up the boost or rpm. Rpms an boost dropped to 18psi and 1800rpm and stayed there. Was going about 55 by the time I got to the top of the hill. Got to the top and it slowly picked back up to 75. Am I just expecting too much out of a stock truck?
 

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Not being there, and the fact my truck hasn't been stock for over 20 years, I would say it sounds normal. I'm guessing EGTs were topping out at about 900?
 

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Discussion Starter · #17 ·
I just got my egt gauge hooked up after that run so I’m not sure where they were at. If that’s where my truck is at for stock power I think I might put some injectors and a fuel plate in it to see if it will give it just a little more. I don’t want to go to crazy. What are your thoughts on it?
 

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No need to buy injectors. I have been running stock Bosch the life of the truck. A #11 fuel plate and 15 degrees of timing put me at 293/611. The custom plate I have now put me at 311/756 with stock injectors and turbo. You don't have to spend a ton of money to wake the engine up.
 

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The first time is a bit daunting, but it is really not that difficult. Just a fuel plate change to the #11 worked for me for a long time. The extra timing was mostly for increased fuel mileage. There are several ways to do it. I use a gauge similar to this one. Dodge Cummins w/P7100 Timing Tool Kit | Pure Diesel Power
 
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