Car surges as if gas being turned off, then back on again

Reply

  #1  
Old 05-28-10, 05:51 AM
Banned. Rule And/Or Policy Violation
Thread Starter
Join Date: May 2007
Location: Wisconsin
Posts: 8,629
Car surges as if gas being turned off, then back on again

'92 Dodge Spirit, V-6.

This has been going on quite steadily now for about 2 weeks. The car behaves identical way as if you give it gas and let off the throttle, repeatedly. No misfire or engine backfire upon reengagement, either, seemingly to rule out electrical, according also to the opinion of an older auto part guy, after I thought about simply replacing the coil ($41) and he said he doubted that was it. He thought I should get a backfire if electrical kliled then came back on.

If I was to willy-nilly throw parts at it, I think I'd go the junkyard route. And as of right now I'm thinking about replacing the TPS...after I remove the air cleaner for first time ever, to see if any lose connection hiding under there. Bad ground? Fuel pump? Also I haven't had the opportunity, due to work demands to even check out my Haynes manual wiring diagram on the fuel circuit, which I really should do.

The other day it got real bad after I drove about 5 miles it started in and got so bad, that I thought I'd have to ditch to the shoulder, when I was cruising on the highway. But I did make it the remaining 10 miles or so, with my head snapping forward and back, and thrust to spinning components causing cluncking in trans or engine with this going on. And THAT concerns me, as that cannot be good, to have that going on all the time. Like having car shift in and out of passing gear repeatedly.......only worse.

Took it to reputable shop(supposedly) and they drove it 23 miles over 2 days on 3 occassions and even owner said it never did it for him when he drove it home, (and kept it over night,) even on interstate! And he even warmed the car up in advance to make sure say if a component gets hot, to see if that adds something to the cause. Naturally, it did not do it for him. And I told him I KNEW that was going to happen. Cost me $60 for absolutely nothing!!! May as well have burned the money with a match. I work so very very hard for $60. No test meter was even ever put on the car - say the fuel rail, nor voltmeter testing at fuel pump. Don't they have remote tester you can run into the cabin to oberve fuel pressure while driving the car? If so, he really should have had one on there from the get go, from the symptom I told him.

I'd try to figure this out myself, but am swamped with work (and should be working right now!!!) and HAVE TO have my car now in the worst way.

He is not so certain it even IS the fuel pump, even though with 141,000 miles it may be due. He said it could be a number of lesser costly part/procedures causing this, like debris/rag gathering to the fuel pump sock, some relay, ground, some bad connection somehere, something with the TPS/computer acknowledgement. ???? He wanted to throw a fuel filter at it, but I said I doubted that is it, due to never starves upon accelerating, and I did not want to throw more money at it, without results(at his garage, anyway)......probably would have cost $75 MORE. Forget that noise!
 
Sponsored Links
  #2  
Old 05-28-10, 08:43 AM
Member
Join Date: Aug 2006
Location: santa fe /texas
Posts: 998
'I' would think,that if it were fuel pressure related-it would be a slower loss of power.NOT the jerking on/off as you describe.
now that i have told you what i don't think it is.
i haven't a guess at what it could be!
possible loose electrical connection/ground??

& yes, there is a way to run a fuel pressure guage up & tape it to the windshield.
 
  #3  
Old 05-28-10, 03:41 PM
Unclediezel's Avatar
Member
Join Date: Dec 2006
Location: Northeastern PA.
Posts: 2,230
No Warning lights??????

Does it have a Tach, and does it behave normally during the symptom????

TPS should set a lamp, since Throttle opening wouldnt match what the SMEC expects based on MAP value.

If the TACH corresponds to the "Dropout" youre feeling, , ie...Dropping to zero, or rapidly "Bouncing"momentarily, Suspect ignition. What you describe is a coil wire "Arcing" under Engine movement.
 
  #4  
Old 05-28-10, 04:02 PM
Banned. Rule And/Or Policy Violation
Thread Starter
Join Date: May 2007
Location: Wisconsin
Posts: 8,629
Originally Posted by Unclediezel View Post
No Warning lights??????

Does it have a Tach, and does it behave normally during the symptom????

TPS should set a lamp, since Throttle opening wouldnt match what the SMEC expects based on MAP value.

If the TACH corresponds to the "Dropout" youre feeling, , ie...Dropping to zero, or rapidly "Bouncing"momentarily, Suspect ignition. What you describe is a coil wire "Arcing" under Engine movement.
No warning lights. Code 33 and 55 (an end of codes, code)......33 makes no sense(would not seem to apply), and says in Haynes manual that code numbers may not apply to all models.

Does not matter if I am on the level, going up hill, down hill.

No tach in my 92, wouldn't you know it. My 90 and 91 Spirits both had tachs.

Since I have been thromping on the gas lately, the problem has now diminished. It is only sutbtle at times. Nothing jerking me around like 2 days ago and before that, when it seemed like it was a 100% momentary split second shutdown.
 
  #5  
Old 05-28-10, 04:10 PM
Banned. Rule And/Or Policy Violation
Thread Starter
Join Date: May 2007
Location: Wisconsin
Posts: 8,629
Originally Posted by newtofta View Post
'I' would think,that if it were fuel pressure related-it would be a slower loss of power.NOT the jerking on/off as you describe.
I don't know with these high fuel pressure cars (48 psi) today. In fact I am not even sure about that theory that if it is electrical related, that there would be a backfire, the way the old cars would do if you turned off the key while cruising, and then turned the key back on.These newer type computer cars are a you know what in the you know where. Too many things that can cause one problem.


now that i have told you what i don't think it is.
i haven't a guess at what it could be!
possible loose electrical connection/ground??
Unclediezel?
 
  #6  
Old 05-28-10, 08:35 PM
Member
Join Date: Aug 2006
Location: santa fe /texas
Posts: 998
in-my experience-(limited in driveability)-even when an electric fuel pump 'quits'-it still takes 5-15 seconds for the fuel pressusre to drop to a spec '?' that is too low to deliver fuel

that is where the pressure guage on the windshield -comes into play as a problem -elimination.
i/e-45 psi/eng quits-not a fuel pump.

follow me-??
 
  #7  
Old 05-30-10, 05:41 AM
Member
Join Date: Jan 2006
Location: Ontario, Canada
Posts: 759
Wouldn't hurt, if you have, or could borrow an old (cheap) analog (needle type arm) multimeter/ohmmeter, to test TP sensor yourself. Car shut off obviously, Pull connector off, and touch your probes on pins of TP sensor, with meter set to ohms. Not 100% sure which ones now, but when you touch probes on 2 of them, and move throttle linkage, needle will sweep on meter to coincide with TP sensor. Once you find the 2 terminals that work, have someone push gas pedal slowly and steady, all the way to floor, and back up as you watch the needle on meter. Have them do it a few times. Slow and steady is the trick, and if the needle on meter suddenly drops back, then jump back up anytime during the test, then you've found a dead spot in the TP sensor, and likely your problem. If needle on meter goes smooth and steady with no dropping off, TP sensor should be o.k. I'd also clean all terminals and connectors with electrical spray, then add a dab of di-electric grease to make sure of good, clean,protected connection. Also, try to pay attention to fuel level as well as temperature outside when problems occur. I had one that acted up on hot days, especially with low fuel in tank, but ran great on cool days. It was fuel pump, would run great when fuel level was up (cooled the pump) and/or weather was cool, but after sitting in the sun, and fuel got hot, would act up shortly after . Cool, pressure was 49psi, and dropped off to 5 psi, and stall when pump got hot. Let it sit and cool, and away it went for a while again.
 
  #8  
Old 05-30-10, 11:16 AM
Banned. Rule And/Or Policy Violation
Thread Starter
Join Date: May 2007
Location: Wisconsin
Posts: 8,629
Originally Posted by newtofta View Post
follow me-??
Yes. .............................................
 
  #9  
Old 05-30-10, 11:30 AM
Banned. Rule And/Or Policy Violation
Thread Starter
Join Date: May 2007
Location: Wisconsin
Posts: 8,629
Originally Posted by Mike.B View Post
Wouldn't hurt, if you have, or could borrow an old (cheap) analog (needle type arm) multimeter/ohmmeter, to test TP sensor yourself. Car shut off obviously, Pull connector off, and touch your probes on pins of TP sensor, with meter set to ohms. Not 100% sure which ones now, but when you touch probes on 2 of them, and move throttle linkage, needle will sweep on meter to coincide with TP sensor. Once you find the 2 terminals that work, have someone push gas pedal slowly and steady, all the way to floor, and back up as you watch the needle on meter. Have them do it a few times. Slow and steady is the trick, and if the needle on meter suddenly drops back, then jump back up anytime during the test, then you've found a dead spot in the TP sensor, and likely your problem. If needle on meter goes smooth and steady with no dropping off, TP sensor should be o.k.
Very detailed and easy to follow. Thanks. Will give that a go when I get thru with this work load I am uner right now.

I'd also clean all terminals and connectors with electrical spray, then add a dab of di-electric grease to make sure of good, clean,protected connection.
A motor head that lives by me is of the opinion that dielectric grease means it conducts electricity - so that by adding it, you naturally have better conductivity of electricity. I did not have the heart to correct him. I am of the opinion I best most people think that. An ohm meter will show such grease or oil to be 100% NON-conductive.

Also, try to pay attention to fuel level as well as temperature outside when problems occur. I had one that acted up on hot days, especially with low fuel in tank, but ran great on cool days. It was fuel pump, would run great when fuel level was up (cooled the pump) and/or weather was cool, but after sitting in the sun, and fuel got hot, would act up shortly after . Cool, pressure was 49psi, and dropped off to 5 psi, and stall when pump got hot. Let it sit and cool, and away it went for a while again.
I HAVE been paying attention to that. I believe any association on my part would be imaginary. I think it does it - whenever.

The problem has now changed from going to absolute power failure, to just a mild intermittant hickup. Like -at first..... either all or say half the cylinders were shutting down, where now..... maybe one cylinder? hiccups like only involving one cylinder? It comes and goes so fast that it is hard to discern.

Always: When I throttle it, it has get up and go snort thru the entire power range. Never even a hiccup, ever. Problem only occurs when cruising town or highway at low throttle - only. Never while into the throttle. Car has never stalled out on me (crossing my fingers), the way it did when fuel pumps went out in my high-mileage 4-banger Dodges.
 

Last edited by ecman51; 05-30-10 at 11:45 AM. Reason: Keyboard making mistakes
  #10  
Old 06-02-10, 06:39 AM
Banned. Rule And/Or Policy Violation
Thread Starter
Join Date: May 2007
Location: Wisconsin
Posts: 8,629
It's Baaack!

Here I have gone now.... what....a couple weeks?, of it either not doing this or to a greatly lesser degree, without getting that head jerking effect.

Well, this morning, it started in again about 7 miles out of town when I was out on the highway cruising(clear skies/about 58 dgrees out). It most definitely shuts off instantly and turns back on again within a fraction of or 1-2 second(s), over and over again, causing the gears in the car to clunk from this non-sensical surging. It is not as if the gas dims down. It is suddenly on, suddenly off, suddenly on, etc.

I need to know, with today's cars, if the fuel pump quits, that, coupled with this, along with the fact the injectors need like 49 psi to operate, that if the electrical stops with the fuel, that it will suddenly stop the fuel flow or not ??? Yes or no? I mean suddenly. I have to have that answer.

Years ago, with mechanical pumps and carbs, the gas flow really could not come to a sudden stop. But maybe with today's electrical fuel pump and injectors, maybe it can?

Need to know whether to analyze the fuel circuit?, or instead focus on say loose electrical wires in primary circuit or a bad coil(secondary) or bad auto shutdown relay, that will both kill the gas and coil at same time (although for thatpossible prognosis perhaps I could wire my voltmeter to the coil somehow remotely so I could see what happens to the primary side coil voltage in the cabin.)
 
Reply

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are Off
Pingbacks are Off
Refbacks are Off


Thread Tools
Search this Thread
Display Modes