hesitation

[Logos5]

97 6.5T 2500Suburban. 242,000 miles. the problem is that their is a jerking, hesitation of the engine between 1600-1900 rpm no matter what gear it is in or speed. If I step on the gas the problem goes away. My mechanic said that there was a 1217 code set, which indicates FSD. But the code goes awayThe FSD was replaced about 12,000 miles ago with an after market one. The mechanic thinks it is the trottle position sensor because it only happens at cruising speed. He is thinking that there is a dead spot in the sensor. Is the sensor like a variable potentiometer?. Any suggestions? Thanks.

[mangus34]

have the same problem in my 95 suburban. Changed throttle position sensor. Didn't help.Still got problem.

[tom.mcinerney]

>>thinking that there is a dead spot in the sensor. Is the sensor like a variable potentiometer?.

The 'gas pedal' activates (consists of) a series of three pots in parallel {properly on same shaft} which are monitored for consistent (each the same) output which the PCM then accepts as valid input.

These do wear. Some have corrected by drilling hole somewhere in case and then spraying with contact cleaner. maybe search relevant posts.

[BobND]

What happens if you engage the cruise control at the troublesome speed?

[JohnC]

Do you have EGR?

[Logos5]

BobND,
The problem occurs even when in cruise control. No matter what speed.

JohnC,
EGR? Is your question: is it functioning properly (i.e. vacuum, voltage?) Thanks.

[BobND]

I would think since the problem occurs in cruise control mode, also, that would rule out the throttle position sensor (gas pedal), since in cruise the pedal returns to idle position, and speed is controlled by the PCM.

[JohnC]

Originally posted by Logos5:
EGR? Is your question: is it functioning properly (i.e. vacuum, voltage?) Thanks. No, simply do you have it? Your symptoms have been linked to a sticky EGR valve, at least on earlier trucks. I don't know if it would necessarily set a code on later trucks or not.

[Logos5]

JohnC,
I will check it out and get back to you. Thanks.

[Logos5]

BobND,
Thanks for the heads up on the cruise control. Great troubleshooting idea.

[Brian Wood]

I have this problem also with my 99 Sub 2500 4X4. Replaced OPS,FSD,Heavy duty lift pump, cleaned battery cables with no results. No codes present. The IP was replaced under warranty at 110,000.The missing started around 120,000. At 130,000 now. One thing I notice it will run ok for a few days after I've work on it and each time I replaced the fuel filter but then it comes back. So I'll start looking at the wiring harness to see if there is a short that is disturbed while replacing these items that heals itself temporary a couple of days then starts back to missing. If someone has a answer to the problem I think they would surely releave some head aches out here. Brian

[Logos5]

Brian,
Thanks for the heads up on possible bad wiring.

JohnC,
Sorry it took so long to get the answer to your question on whether I have EGR. Ther is NO EGR or vent solenoids. There is NO EGR control pressure sensor. There is no EGR valve. Also there is NO MAF sensor. The MAP and the IAT are the only two sensors on the top of the intake manifold.

Could the problem be associated with the MAP or the Vehicle Speed Sensor?

The manual I have (1997 C/K Truck Service Manual Book 2 of 2)shows the same picture for the MAP and VSS sensor. It indicates tha the VSS sensor is located behind the instrument panel. Thanks for the help.

[Logos5]

Any suggestions anyone?

[JohnC]

Originally posted by Logos5:
Any suggestions anyone? Get a Tech II and record the data stream while it's acting up.

P1217 could cause the problem. It could be the fuel solenoid or possibly the FSD. Since you're not complaining about stalling, I'd lean toward the solenoid. Try a double dose of a Diesel fuel system cleaner/lubricity additive.

[rjwest]

Code is Fuel solenoid responce time to long..

Could be IP or bad FSD.

I had a new FSD fail in only a few weeks..( I always get the Rejects )

[Barry Nave]

And on my 95 it's code 35. Couple of times I'v had a 36.
The ses has been on and off more lately than before. Probley on browed time :(

[wfyehl]

A little over a year ago I had to have the stealership install a new fuel shutoff selonoid. My wife was driving the Burb, and it stalled in the middle of traffic. Once replaced, it ran fine again. It is a pricey item from the stealership, but if you have to have it now, you have to pay their price. I was able to chew them down to wholesale, but there were others issues I had with the stealership that I won't go into here.

Bill

[rjwest]

I have a used/working solenoid if anyone is interested.

[Logos5]

rjwest,
How difficult is it to replace the fuel solenoid? Do you have to remove the Injector pump assembly or can you just remove the solenoid? Do you need any special tools once the new solenoid has been replaced? How much for your solenoid? Thanks.

[JohnC]

There's the shutoff solenoid, easy to replace, but not your problem. Then there's the fuel metering solenoid. I don't know how difficult it is to replace. I think it can be done but there may be serious calibration issues afterword. Someone else may know better. Just don't want you to confuse the two...

[Logos5]

JohnC,
Thanks for the clarity. After further searching on this website, I found a great picture identifying the location of the fuel solenoid and the fuel shut-off solenoids. Both located on the IP(www.thedieselpage.com/t/fdsresistor.htm)
From what I have been reading and the fact that rjwest has an individual "solenoid" it sounds like it can be done. But whether it can be done without removing the IP, it is unclear.

The HELM manuals ($135 kind) does not show how to disassemble the IP only to remove it from the engine.

Does the repair manual for the 6.2 and 6.5 offered by thedieselpage include this type of disassembly instruction or does it just show how to remove and set up the IP as a unit? I'd be willing to buy this manual if it is more instructive than the manual I already have.

From reading the different articles on this website it appears that if I don't mess with the electronics (i.e. resistor or change the TDC) then I should be able to replace just the solenoid. Does anyone have experience just replacing the fuel solenoid?

Going back to the original DTC P1217 Fuel Solenoid Response Time too Long; with out a scan tool I can't check the time. Where can I get a scan tool relatively cheap?

Thanks for all your help.

[Barry Nave]

From reading the different articles on this website it appears that if I don't mess with the electronics (i.e. resistor or change the TDC) then I should be able to replace just the solenoid. Does anyone have experience just replacing the fuel solenoid-


This is what I've been waiting on to do/try with my pump. My issue is as yours though untill I'm sure that it can be just a R&R I can't have my truck down.
The pump does not need to be removed. With John C I also don't know if there is any timing issue's.

[wayne zylik]

I am having a simular problem now with my Truck it is doing all the same things but also at Idle it is surging and bucking I replaced the fuel filter and FSD and forgot to install the Resistor it ran the same and when I installed the resistor it ran a bit better but nothing to write home about I have recently replaced the Battery Cables both sides and the Ignition Switch.Could the wieght of oil be causing a problem this is the first year that I am running 10w30 DMO as I am suspecting the OIl Pressure Switch maybe causing a Problem .BTW this problem does not occur all the time.

[rjwest]

Sorry I confused you.... Miss read or posted in wrong thread...


FUEL SHUT OFF Solenoid is on front of IP
and can be replaced easily, That is what I offered.

[BUZZ]

I had IP R&R 30,000 miles ago. The result, I then developed cold start issue, and then a a year or so later started to develop this dead spot, surge, hesitation, when cold. 35, 36 as well. Sold fixed the codes.
I recently bought 2 pumps off ebay and will have them checked and or rebuilt. I believe my issue id the IP. Everything else has been checked.
We will see but IP change is next.

[Logos5]

rjwest,
Thanks for getting back with the info on the fuel shut-off solenoid.

Does anyone know if you can just buy the fuel solenoid that is controlled by the PMD? Or do you have to buy the IP? Thanks.

[Logos5]

Found this on Kennedy's website, regarding the fuel delivery solenoid. It looks like I have to buy an IP. Anyone have a recondition for a good price?

"These seldom fail with the exception of leakage. This is not the delivery solenoid nor is it operated by the fuel solenoid (FSD/PMD) driver. The actual delivery solenoid is not a user serviceable part." - JK

[DmaxMaverick]

If you are confident (and competent) getting inside the pump, any Stanadyne service center can get any individual internal part. It is Stanadyne's policy to sell and service only complete I/P's to a consumer, but many service centers are more cooperative. It is also easy to have the service center test and calibrate a pump, if you have it off already.

[Logos5]

DMAXMAVERICK,
Thanks for the heads up on Stanadyne. Did a web search and found a service/dealer location locally. I will be stopping tonight to see if they will sell individual components. If I get the fuel delivery solenoid I will attempt the replacement myself.

Does the 6.2/6.5 Repair Manual sold by thedieselpage show how to remove and replace the IP and if any special tools are required to set it up? Thanks for your help.

[Barry Nave]

If I get the fuel delivery solenoid I will attempt the replacement myself.

I'm keeping my eyes on your lead. You could be the answer to my problem. When it works for you,I'll dive in also.

[Logos5]

I stopped by my local Stanadyne Service Dealer. They said that they will sell me components, no problem. BUT, the fuel delivery solenoid is not a "bolt in" component (the fuel shut-off solenoid is). This soleniod is "pressed in place" (may not be the best way to describe the replacement process) and then indicated (verniers or dial indicator) to make sure it is properly seated and located. It is then bench tested to see if the setup is correct. IF you have the proper setup tools and know the correct positioning of the solenoid then go for it. I will not attempt this replacement myself. I don't have the time, tools or experience.

Here is a another thought I think is important to consider. The mileage on the IP. One of the more seasoned techs (at Stanadyne) said it was his experience that when you start replacing components on the IP (especially those with high mileage)then the domino effect usually happens (something else breaks). I know these guys are trying to sell a service, but I think it is a good point to consider.

Personally, if I am going to remove the IP and considering the mileage (245,000) I am going with a rebuilt one.

Also this dealer will sell me the IP without the FSD. Cost of the rebuilt IP - $850.
Cost of the IP without the FSD -$690.

Now do I buy the scan tool first or the IP??? Hmmm! I would like to get the scan tool first so I can verify fuel solenoid close time (2.4msec)which set the DTC code (1217)in the first place.

If I can get my local mechanic to verify the timing then I will replace the IP. I'll let you know how I make out. Thanks again for everyone's help.

[rjwest]

Closure time is a function of the pump. You can not
adjust it, The only adjustment is the rotation of the pump, .


? 245K miles on truck/engine. ?

If it runs, why bother????

[Barry Nave]

If it runs, why bother????

This is where I'm at/from. Been running with the code 35 for a year now. My pump at 100K seems fine Starts,runs good and MPG has not changed. It's that ses that get to me :rolleyes:

[Logos5]

rjwest and bnave95,
The truck is hesitating and running like it is not getting enough fuel. If I step on the accel pedal it takes right off, but after I take my foot of the pedal it hesitates again. The only code set was 1217 which indicates a problem with the fuel delivery solenoid.

I am going to buy the scan tool from Autoenginuity so I can do my own diagnosis.

From reading other threads on IP setup, y'all talk about rotating the pump to the drivers side or passenger side. I have never removed one of these pumps, so bear with my ignorance. The pump comes as an assembly. What is actually being rotated? The pump body or am I missing something. Also the other threads indicate you need a scan tool to set up the IP after it is replaced - correct?

[Logos5]

rjwest,
Another question on Autoenginuity. Do I need to buy the enhance version of the software in order to set up the IP after install?

[rjwest]

I have a Carcode scanner not Autoequity ;
Has the features but I have not verified it works.

The whole pump is turned to set mechanical timing.

I am not an expert, failed at timing my pump....

[Logos5]

rjwest,
Thanks. I grabbed the wrong logon name. It was GMC Hauler that did a lot of work with Autoenginuity.

Thanks again.

[Barry Nave]

The pump body or am I missing something. Also the other threads indicate you need a scan tool to set up the IP after it is replaced - correct? -

Yes on the pump body. When replacing a pump you will see a line on top of the pump and the mating surface. Note where,how the pump line matches. If it is off,say more to the driver side then scribe a line on the mating surface to get the new pump close to where the old pump was.
Then it does take a scan tool that is able to set the "Top Dead Center Offset" TDCO. This is a learn vaule that can only can be perform with the scan tool. Moving the pump, the scan tool will show you the crank Deg.This is where you will be moving the pump,driver side wiil advance+ and pass. side will retard-. Norm. +3.5 and TDCO @-1.95. Knowing and learning how to use the tool is the hard part and the steps involed.

[Logos5]

Bnave95;
Thanks for helping me understand the alignment of the pump. I am purchasing the Autoenginuity scan software and interface. As soon as I get this setup and hooked up to the truck then I will probably be back asking more questions. Before I replace the pump I want to get a before and after scan. Thank you.

[BUZZ]

I inserted clear tubing on fuel feed to IP and the injector return lines. No air in to the pump but air in the return lines.
I have suspected this pump was sucking air when cold for some time.
Swapped out the IP this weekend. Starts like it did when I first got it and no hesitation. The pump I replaced had less than 50,000 miles and has been going south for over a year. Personally I think this pump was crap out of the box.
I am a happy camper again.
Buzz