Truck="missing"or"starving"engine of fuel during acceleration-EGRvalve or Injectors?

[antman33]

Truck="missing"or"starving"engine of fuel during acceleration-EGRvalve or Injectors?

My 98 GMC SONOMA 2.2 LITER 4 CYLINDER has been seemingly "missing" or "starving" for about 4 months now. It drives ok then, during acceleration, it seems to "miss" and semi "jerk" the entire vehicle - as though the engine simply isn't getting enough fuel to continue the acceleration process.

Also, the CHECK ENGINE light is popping up on occasion.

I assumed it was either clogged injectors or an old fuel filter so I replaced the filter (which did nothing?) but before I spent the grand on new injectors I was told about this EGR valve thing. Since this is a MUCH cheaper fix I was intrigued as to the validity of this as a solution.

Any ideas?

 

[Molson02536]

My 98 GMC SONOMA 2.2 LITER 4 CYLINDER has been seemingly "missing" or "starving" for about 4 months now. It drives ok then, during acceleration, it seems to "miss" and semi "jerk" the entire vehicle - as though the engine simply isn't getting enough fuel to continue the acceleration process.

Also, the CHECK ENGINE light is popping up on occasion.

I assumed it was either clogged injectors or an old fuel filter so I replaced the filter (which did nothing?) but before I spent the grand on new injectors I was told about this EGR valve thing. Since this is a MUCH cheaper fix I was intrigued as to the validity of this as a solution.

Any ideas?

Start with the simple and have your Sonoma scanned for the DTC codes. Auto Zone scan free of charge, it could be a simple TPS having a bad spot and will need to be replaced or a faulty knock sensor.

Start with the scan and also would not be a bad thing to clean out your engine with http://www.seafoamsales.com/.

Read this post http://gmcowners.com/gmc-forum/showthread.php?t=13770 Good luck and keep us posted.

 

[antman33]

Start with the simple and have your Sonoma scanned for the DTC codes. Auto Zone scan free of charge, it could be a simple TPS having a bad spot and will need to be replaced or a faulty knock sensor.

Start with the scan and also would not be a bad thing to clean out your engine with http://www.seafoamsales.com/.

Read this post http://gmcowners.com/gmc-forum/showthread.php?t=13770 Good luck and keep us posted.

Ok quick update - called Auto Zone and they no longer do the free CHECK ENGINE LIGHT scan, apparently its a chain-wide "we no longer do" thing? But, the salesman was nice enough to tell me that AAMCO does do the scan for free so I am off to get it checked there.

Also, when I replaced my fuel filter I added a product similar to seafoam to my gas tank - cant recall the name of it - but it claims to do just what you claim seafoam does. Something tells me that seafoam is better so as soon as I use up this tank of gas I will pour in (w a funnel, as you said) a can of seafoam.

Thus far, I have used about a 1/4 tank of the "treated" gas and it does seem to be a slight bit better, but the problem is still there and has always been intermittent so who knows if it is REALLY doing anything or not at this early stage.

 

[antman33]

Ok quick update - called Auto Zone and they no longer do the free CHECK ENGINE LIGHT scan, apparently its a chain-wide "we no longer do" thing? But, the salesman was nice enough to tell me that AAMCO does do the scan for free so I am off to get it checked there.

2 codes came back - P0122 (Throttle Pedal Position sensor A Ckt) & P1626 (Theft Deterrent System Fuel Enable Ckt)

Any idea what these mean?

Also, when I replaced my fuel filter I added a product similar to seafoam to my gas tank - cant recall the name of it - but it claims to do just what you claim seafoam does. Something tells me that seafoam is better so as soon as I use up this tank of gas I will pour in (w a funnel, as you said) a can of seafoam.

Thus far, I have used about a 1/4 tank of the "treated" gas and it does seem to be a slight bit better, but the problem is still there and has always been intermittent so who knows if it is REALLY doing anything or not at this early stage.

 

[Molson02536]

Ok quick update - called Auto Zone and they no longer do the free CHECK ENGINE LIGHT scan, apparently its a chain-wide "we no longer do" thing? But, the salesman was nice enough to tell me that AAMCO does do the scan for free so I am off to get it checked there.

2 codes came back - P0122 (Throttle Pedal Position sensor A Ckt) & P1626 (Theft Deterrent System Fuel Enable Ckt)

Any idea what these mean?

Also, when I replaced my fuel filter I added a product similar to seafoam to my gas tank - cant recall the name of it - but it claims to do just what you claim seafoam does. Something tells me that seafoam is better so as soon as I use up this tank of gas I will pour in (w a funnel, as you said) a can of seafoam.

Thus far, I have used about a 1/4 tank of the "treated" gas and it does seem to be a slight bit better, but the problem is still there and has always been intermittent so who knows if it is REALLY doing anything or not at this early stage.

Replace your TPS (Throttle Position Sensor). best place for you to pick one up is at the Salvage Yard. $5.00 and it`s your when you pick it out your self from a Salvaged Sonoma. At that price, pick up two for good luck

This will address the P0122 code and i would not worry about the P1626 for now. Good luck and keep us posted.

 

[antman33]

Ok so I ran through a full tank of injector cleaner (not seafoam but I do plan on using it) and the "missing" issue seemed to vanish almost entirely - not completely, but almost entirely. So here is the weird part - as my tank emptied the problem grew worse.

My tank is 18.5 gallons and over the years I have figured out that the "fuel" light pops on with about 2 gallons left in the tank. This specific tank (which was filled w the injector cleaner) seemed to run smoothly until a few miles AFTER the "fuel light" popped on. Basically, when the tank was near empty the truck started to "miss" and "surge" again - and this time it was BAD - almost to the point of "non-operational". This then reminded me of the last time this happened, and it was the exact same scenario - the tank was near empty and the truck freaked.

Yesterday I re-filled the tank and PRESTO, the "check engine" light vanished and the truck was running again - not perfectly but about 80% better.

So, my old man (who worked for NAPA for 40 years) mentioned this: Apparently an old colleague of his had a similar issue with an older GM PICKUP TRUCK (v8 engine). When his tank would get low, his truck would start to "miss" badly - when they finally found the problem, it was the filter/sock in the tank itself.

I have already replaced the "fuel filter" outside the tank, so, can we assume that MY fuel pump may have some sort of a filter on it as well? And if this is the case, can we also assume that if we replace said fuel pump in its entirety, the issue could be solved?

 

[Molson02536]

Ok so I ran through a full tank of injector cleaner (not seafoam but I do plan on using it) and the "missing" issue seemed to vanish almost entirely - not completely, but almost entirely. So here is the weird part - as my tank emptied the problem grew worse.

My tank is 18.5 gallons and over the years I have figured out that the "fuel" light pops on with about 2 gallons left in the tank. This specific tank (which was filled w the injector cleaner) seemed to run smoothly until a few miles AFTER the "fuel light" popped on. Basically, when the tank was near empty the truck started to "miss" and "surge" again - and this time it was BAD - almost to the point of "non-operational". This then reminded me of the last time this happened, and it was the exact same scenario - the tank was near empty and the truck freaked.

Yesterday I re-filled the tank and PRESTO, the "check engine" light vanished and the truck was running again - not perfectly but about 80% better.

So, my old man (who worked for NAPA for 40 years) mentioned this: Apparently an old colleague of his had a similar issue with an older GM PICKUP TRUCK (v8 engine). When his tank would get low, his truck would start to "miss" badly - when they finally found the problem, it was the filter/sock in the tank itself.

I have already replaced the "fuel filter" outside the tank, so, can we assume that MY fuel pump may have some sort of a filter on it as well? And if this is the case, can we also assume that if we replace said fuel pump in its entirety, the issue could be solved?

Yes but you do know the fuel pump screen is replaceable it self, but if you have more then 150,000 miles or close to it. You may want to replace the sending unit, there only rated for up to 150,000 miles and anything after that is borrowed time.

Good luck and keep us posed.

 

[antman33]

Haha, what I know about cars could fit nicely into an ant's pocketbook and still have room left over for a turkey dinner ...

Funny thing is that my truck just hit the 145,000 mile mark so, if we were to assume it was a fuel pump issue, I was just going to replace the entire thing anyway - which is what I am assuming you are hinting at?

Ok, so here is where I get your pro opinion - given all of the symptoms I have described in this thread - 1) The "missing or "surging", 2) the fuel filter replaced, 3) "check engine light" coming off and on, 4) the 2 error codes given, 5) 1 full tank mixed w "injector cleaner" which seemed to help? - What or where would you proceed with next?

 

[Molson02536]

Haha, what I know about cars could fit nicely into an ant's pocketbook and still have room left over for a turkey dinner ...

Funny thing is that my truck just hit the 145,000 mile mark so, if we were to assume it was a fuel pump issue, I was just going to replace the entire thing anyway - which is what I am assuming you are hinting at?

Ok, so here is where I get your pro opinion - given all of the symptoms I have described in this thread - 1) The "missing or "surging", 2) the fuel filter replaced, 3) "check engine light" coming off and on, 4) the 2 error codes given, 5) 1 full tank mixed w "injector cleaner" which seemed to help? - What or where would you proceed with next?

Start with the simple and reset your PCM. You can do this by turning your ignition switch to the on position. (engine not running) and then pull the ECM fuse out for 1 min then place back in.

Once fuse is back in, turn ignition switch off for 10 seconds and on again for 30 seconds (engine not running). After 30 seconds up, start the engine and let idle for 5 min then go for a test drive. If the engine stalls after you fisrt start it, let it. The PCM is just relearning the engine's condition and taking all the input for the sensors.

You should not have any codes stored in your PCM and any codes that you can pull will be new or active for you to address. If your P0122 code is still there, then inspect the wire leads to your TPS or replace your TPS.

Good luck and keep us posted.

 

[antman33]

Ok will do. Any shot you'd have any idea where the TPS is on my GMC 98 Sonoma? I should have no problem getting a new one from a parts house - but I honestly have ZERO idea where it is located?

Actually, would you know of a website where I'd be able to find a schematic for my truck so I can more easily find where all of these various parts are located (in case I can replace them myself?)

 

[antman33]

Ok will do. Any idea where the TPS is located on my 98 GMC SONOMA?

Actually, if you could direct me to a website or some place where I'd be able to find a schematic for my specific truck it would be greatly appreciated. Just in case I can do any (or all) of these fixes myself - I'd like to know where to start haha.

 

[antman33]

Start with the simple and reset your PCM. You can do this by turning your ignition switch to the on position. (engine not running) and then pull the ECM fuse out for 1 min then place back in.

Once fuse is back in, turn ignition switch off for 10 seconds and on again for 30 seconds (engine not running). After 30 seconds up, start the engine and let idle for 5 min then go for a test drive. If the engine stalls after you fisrt start it, let it. The PCM is just relearning the engine's condition and taking all the input for the sensors.

You should not have any codes stored in your PCM and any codes that you can pull will be new or active for you to address. If your P0122 code is still there, then inspect the wire leads to your TPS or replace your TPS.

Good luck and keep us posted.

Ok - will do.

Actually do you have any idea where I can find a schematic for my specific 98 GMC SONOMA pick up?

I honestly have ZERO idea where the TPS is located ... Actually I have no idea where any of these parts are haha.

 

[Molson02536]

Ok - will do.

Actually do you have any idea where I can find a schematic for my specific 98 GMC SONOMA pick up?

I honestly have ZERO idea where the TPS is located ... Actually I have no idea where any of these parts are haha.

Think the fuse panel is located on the drivers side at the end of the dash and the fuse label is on the inside of the access panel. The TPS is located on the throttle body opposite side of where the throttle cable is located . Inspect the wire leads and replace the sensor it self if the wires are free from damage.

Here is a link to your throttle body and #6 is your TPS.
http://www.compnine.com/index.php?u...delid=7078&capuid=1&majorgroup=03&grouptype=B

and #531 is your throttle body on the intake manifold.
http://www.compnine.com/index.php?u...delid=7078&capuid=1&majorgroup=03&grouptype=B

Keep us posted and good luck.

 

[antman33]

Wow those pictures are PERFECT! I am going to try that one today since (in a totally unrelated matter) it looks like I popped the fuse for the 2 "extra cig lighters". I guess I overloaded it w/ too many items over the weekend?

Can't thank you enough - so let me run this one by you ...

My old man has had a theory that the fuel pump filter thing is bad (reference previous posting above for entire story?) so he told me to fill the tank and pay attention to the worst times the truck "misses" and the relation to how full/empty the gas tank is.

Since re-filling the tank seemed to temporarily "solve" the issue, he had me simply keep the tank "full" and pay attention to the levels of the tank and when the "missing" issue returned. Well, I have now gone through 3 tanks and on each occasion the "missing" issue returned upon the tank falling below the "1/2" full mark - plus, the lower the tank got, the worse the "missing" seemed to get.

Does this semi prove his theory that the fuel pump assembly should simply be replaced? And, if so, does that entire fuel tank have to come out or can we simply replace the fuel pump without removing the entire fuel tank?

I ask this because we are considering doing this job ourselves - and if the tank must be removed we will most likely NOT do it outselves.

 

[Molson02536]

Wow those pictures are PERFECT! I am going to try that one today since (in a totally unrelated matter) it looks like I popped the fuse for the 2 "extra cig lighters". I guess I overloaded it w/ too many items over the weekend?

Can't thank you enough - so let me run this one by you ...

My old man has had a theory that the fuel pump filter thing is bad (reference previous posting above for entire story?) so he told me to fill the tank and pay attention to the worst times the truck "misses" and the relation to how full/empty the gas tank is.

Since re-filling the tank seemed to temporarily "solve" the issue, he had me simply keep the tank "full" and pay attention to the levels of the tank and when the "missing" issue returned. Well, I have now gone through 3 tanks and on each occasion the "missing" issue returned upon the tank falling below the "1/2" full mark - plus, the lower the tank got, the worse the "missing" seemed to get.

Does this semi prove his theory that the fuel pump assembly should simply be replaced? And, if so, does that entire fuel tank have to come out or can we simply replace the fuel pump without removing the entire fuel tank?

I ask this because we are considering doing this job ourselves - and if the tank must be removed we will most likely NOT do it outselves.

Most guys will remove the Bed of the pick up truck to get to the fuel tank sending unit. Just make sure you replace the bolts for the bed when reinstalling it and make sure the ground wire for the sending unit is good, or your going to have issues. Note also the fuel pump has a expected life of 150,000 miles and anything over that is considered borrowed time.

Good luck and hope this helps. http://www.compnine.com/index.php?t...=S&makecode=LG&grouptype=B&modelid=7078&uid=1

 

[antman33]

Ok so it looks like I will NOT be doing the fuel pump on my own then haha.

Well the issue seems to be getting worse (the truck has been near non-operational on several occasions) so I think I finally need to make a decision and get something expensive done.

One last bit of info for you (not sure if this has any bearing but here goes?) - the deeper I depress the gas pedal, the less frequently the "missing" issue seems to happen. Basically when the truck is going through one of its "missing" sessions, it seems be worst at the beginning of each gear (my truck is a 5-speed manual) and lower gears seem to be the most frequent - so, the more I depress the gas pedal, the LESS the truck misses.

In fact, on several occasions, I have been able to eliminate the "missing" all together by just going faster.

So, after all of this - do you think you can give me a percentage of what you think your best guess would be as to the solution?

CLOGGED INJECTORS (treated one tank w injector cleaner, seemed to help but issue remains) =

FAULTY FUEL PUMP (truck has 145,000 miles) =

FAULTY TPS (gave this error code but aamco guy said could mean 20 diff things) =

FAULTY EGR VALVE (dads idea - no idea what this does) =

 

[Molson02536]

Ok so it looks like I will NOT be doing the fuel pump on my own then haha.

Well the issue seems to be getting worse (the truck has been near non-operational on several occasions) so I think I finally need to make a decision and get something expensive done.

One last bit of info for you (not sure if this has any bearing but here goes?) - the deeper I depress the gas pedal, the less frequently the "missing" issue seems to happen. Basically when the truck is going through one of its "missing" sessions, it seems be worst at the beginning of each gear (my truck is a 5-speed manual) and lower gears seem to be the most frequent - so, the more I depress the gas pedal, the LESS the truck misses.

In fact, on several occasions, I have been able to eliminate the "missing" all together by just going faster.

So, after all of this - do you think you can give me a percentage of what you think your best guess would be as to the solution?

CLOGGED INJECTORS (treated one tank w injector cleaner, seemed to help but issue remains) =

FAULTY FUEL PUMP (truck has 145,000 miles) =

FAULTY TPS (gave this error code but aamco guy said could mean 20 diff things) =

FAULTY EGR VALVE (dads idea - no idea what this does) =

Check your FPR (fuel pressure regulator) and the vacuum line to it, your FPR is located on your fuel injector rails and there is going to be a vacuum line connected to it. Post back and let me know if that's good and when you pull the vacuum hose from the FPR and fuel is resent, replace the FPR.

Good luck and keep us posted.

 

[antman33]

Check your FPR (fuel pressure regulator) and the vacuum line to it, your FPR is located on your fuel injector rails and there is going to be a vacuum line connected to it. Post back and let me know if that's good and when you pull the vacuum hose from the FPR and fuel is resent, replace the FPR.

Good luck and keep us posted.

Haha, so now you've added a 5th possible solution huh?

Ok so you want me to check the FPR - How exactly does one "check it"? Or how does one know if its "good"? And am I to assume that the "fuel injector rails" are under the hood?

 

[antman33]

Check your FPR (fuel pressure regulator) and the vacuum line to it, your FPR is located on your fuel injector rails and there is going to be a vacuum line connected to it. Post back and let me know if that's good and when you pull the vacuum hose from the FPR and fuel is resent, replace the FPR.

Good luck and keep us posted.

Ok so what exactly does "LET ME KNOW IF THATS GOOD AND WHEN YOU PULL THE VACUUM HOSE FROM THE FPR AND THE FUEL IS RESENT" mean?

Does this mean that if there is fuel coming out of that vacuum port, its bad? Or that it's leaking fuel?

I guess what Id like to know its - what exactly SHOULD we see when we pull the vacuum line off? Shall we see nothing? And if we see fuel does this mean the FPR needs to be replaced?

 

[Molson02536]

Ok so what exactly does "LET ME KNOW IF THATS GOOD AND WHEN YOU PULL THE VACUUM HOSE FROM THE FPR AND THE FUEL IS RESENT" mean?

Does this mean that if there is fuel coming out of that vacuum port, its bad? Or that it's leaking fuel?

I guess what Id like to know its - what exactly SHOULD we see when we pull the vacuum line off? Shall we see nothing? And if we see fuel does this mean the FPR needs to be replaced?

Any signs of fuel from the Vacuum port indicates that the FPR has gone bad and will need to be replaced.

The part is about $15.00 at NAPA or Parts Source.

Good luck and keep us posted.