Recent Topics
What’s the odds..
by Eric Smith
06/19/18 09:51 PM
Who can relate?
by Reddy45
06/19/18 09:43 PM
No more oil changes
by goodtimes
06/19/18 09:19 PM
Separating toddlers from their parents?
by fdcg27
06/19/18 08:50 PM
gm 8.6 truetrac
by Spitter
06/19/18 08:45 PM
New addition to my garage: 2000 Corvette FRC
by MrHorspwer
06/19/18 08:34 PM
Rockauto 5% off
by Spitter
06/19/18 08:32 PM
fumoto oil valve
by Santo
06/19/18 08:19 PM
Grand solar minimum...
by ridgerunner
06/19/18 07:57 PM
Pentofrost coolant $10 Autozone
by PD001
06/19/18 07:49 PM
The things you find cleaning Garage 30+ btls slob
by digger327
06/19/18 07:20 PM
Castrol GTX Magantec 0w20 - 6 pack $21.99 - Amazon
by 04SE
06/19/18 07:07 PM
Havoline Pro DS 5w20 $3.15/quart - Amazon
by 04SE
06/19/18 07:06 PM
Needing New Dipstick
by Geauxtiger
06/19/18 05:11 PM
'98 Mercedes E300TD Rotella T5 10W-30 5k miles
by KenO
06/19/18 04:35 PM
Premium guard oil filters
by Jaha24k
06/19/18 04:09 PM
76 super motor oil- synthetic blend 5w-30
by Jaha24k
06/19/18 04:07 PM
Who makes the Mopar 5038041AA filter?
by Quattro Pete
06/19/18 03:55 PM
Ruger Mini-14, yay or nay?
by 28oz
06/19/18 03:51 PM
USPS long long delivery to BlackStone Labs
by Pajero
06/19/18 02:58 PM
Newest Members
Shassis, Santo, aligoodn, memyself, MichiganKid419
65274 Registered Users
Who's Online
79 registered (77GrandPrix, 2015_PSD, BigCahuna, Aero540T, 7 invisible), 1333 Guests and 42 Spiders online.
Key: Admin, Global Mod, Mod
Forum Stats
65274 Members
67 Forums
285627 Topics
4766614 Posts

Max Online: 3590 @ 01/24/17 08:07 PM
Donate to BITOG
Page 1 of 2 1 2 >
Topic Options
#4547652 - 10/18/17 08:51 PM 1993 K1500 TBI stumbling/surging
BrianF Offline


Registered: 02/25/15
Posts: 549
Loc: Sask, Canada
Well a few months back I picked up a 93 GMC 1500 2 wheel drive rez truck from a friend. 370,600km on the clock and V8. Its got a few problems but otherwise is a decent truck for what I need it for. I replaced the brake switch and got the TCC locking up again but have to chase a low speed surge/stumbling problem. The hose that routes the PCV to the throttle body was rotten so I have that plugged for now. But the main issue is this: once the engine is up to temp it stumbles from idle until around 1500rpm and then it levels out and drives fine on the highway and pulls great through the rev range. It idles fine but once you tip in that is where it stumbles. It never dies.

When it is cold it starts and runs fine. Because of this I was thinking oxygen sensor first. Thinking closed/open loop operation.

Any thoughts?

Thanks!
_________________________
2006 Trailblazer LT. Castrol Edge with Fram Ultra.
2017 Ram 3500 SLT Megacab. Duron SHP 10w30 with Hastings LF608.
1993 GMC 1500. It has oil and still runs

Top
#4547657 - 10/18/17 08:57 PM Re: 1993 K1500 TBI stumbling/surging [Re: BrianF]
mk378 Offline


Registered: 09/27/15
Posts: 1416
Loc: USA
Throttle position sensor, check it with a voltmeter. Also check that the tubing from the MAP sensor to the intake is intact.

Top
#4547671 - 10/18/17 09:08 PM Re: 1993 K1500 TBI stumbling/surging [Re: BrianF]
StevieC Offline


Registered: 08/21/08
Posts: 17116
Loc: Ontario, Canada
Could also be a coil / wires breaking down or leaking spark at specific times. But check the TPS first.
_________________________
'15 Dodge Journey - 90,000 KM's - SSO 5w20
'06 Hyundai Santa Fe - 535,000km - SSO 0w30 (R.I.P)

Top
#4547759 - 10/18/17 11:33 PM Re: 1993 K1500 TBI stumbling/surging [Re: BrianF]
Merkava_4 Offline


Registered: 01/30/07
Posts: 17501
Loc: Clovis, CA
It's acting like the accelerator pump is not squirting when the engine is coming off idle, but this engine is throttle body injected; no carburetor. Hmm...

Top
#4547762 - 10/18/17 11:37 PM Re: 1993 K1500 TBI stumbling/surging [Re: StevieC]
Nick1994 Offline


Registered: 02/19/13
Posts: 10097
Loc: Phoenix, AZ
Originally Posted By: StevieC
Could also be a coil / wires breaking down or leaking spark at specific times. But check the TPS first.
+1
_________________________
2015 Hyundai Sonata 2.4L 79k PU 5w30 & OEM
2000 Toyota Camry 2.2L 228k M1 AFE 0w30 & Wix
1996 Jeep Cherokee 4.0L 146k M1 HM 10w40 & Fram Ultra

Top
#4547855 - 10/19/17 05:17 AM Re: 1993 K1500 TBI stumbling/surging [Re: BrianF]
DNVDMAX Offline


Registered: 11/20/07
Posts: 258
Loc: Richmond, VA
Disconnect the EGR and plug any tubing you disconnected in the process. See if this helps. If so, I can be the EGR, cracked tubing, or the control solenoid.

Carbon may also prevent the EGR from fully seating. After doing the above, I'd also manually manipulate the EGR diaphragm through the slots to check if it's stuck.
_________________________
06 GMC 2500HD DMAX EFILIVE M1 TDT 5w-40 FRAM Ultra
91 GMC K1500 5.7L 5w-30 Quaker State HM Bosch D+
72 Nova 350 SBC 74mm AirWerks Turbo 15w-40 HDEO

Top
#4547879 - 10/19/17 06:08 AM Re: 1993 K1500 TBI stumbling/surging [Re: BrianF]
CourierDriver Offline


Registered: 12/27/09
Posts: 4941
Loc: Tn.
A 24 yr old ride has a right to be stumbling at that age,,lol
_________________________
Don't forget to play nice as much as possible...protect your family and carry what you need for them..PS don't leave home without backup....

Top
#4547901 - 10/19/17 06:43 AM Re: 1993 K1500 TBI stumbling/surging [Re: CourierDriver]
Kira Offline


Registered: 08/19/10
Posts: 5214
Loc: Champlain/Hudson Valley
Spent A LOT of time attempting to diagnose a friend's '89 K1500.
The engine sputtered badly. No real telling if higher revs changed anything though there was some smoothing at speed.
The symptoms pointed to fuel delivery and/or spark management.

THE FIX: Turns out there was a built in tap off on the battery cable (big red one) coming from the clamp. It powered the nascent fuel controller (the flat black 4" X 5" thing held by a bracket right near the throttle body-don't know about '93). The lead swaging of the clamp was full of lead oxide. A new cable fixed all our ills.

FYI: The "computer part for the ignition" was housed in a compartment which was a bulge. Half of this bulge was the back of the glove compartment and the other half reached into the engine bay. The firewall was bulged to accommodate it.

Hope tis helps.

Top
#4547940 - 10/19/17 07:43 AM Re: 1993 K1500 TBI stumbling/surging [Re: BrianF]
kc8adu Offline


Registered: 08/02/05
Posts: 894
Loc: dayton oh
this one is a classic failure.pcv system blocked caused the blowby to enter the tbi through the vent.
rots the fpr spring and drops fuel pressure.
the tbi baseplate passages plug with crud.
clean it up and rebuild the fpr first.
do not plug off the pcv!
fix it.
also make sure the sensor ground cluster at the water outlet is clean and tight.
these 2 things account for the lions share of problems.

Top
#4547960 - 10/19/17 07:58 AM Re: 1993 K1500 TBI stumbling/surging [Re: Kira]
kc8adu Offline


Registered: 08/02/05
Posts: 894
Loc: dayton oh
that black module is the esc.
fuel management is in the ecm.
loss of power via that battery tap will indeed cause lots of issues.
Originally Posted By: Kira
Spent A LOT of time attempting to diagnose a friend's '89 K1500.
The engine sputtered badly. No real telling if higher revs changed anything though there was some smoothing at speed.
The symptoms pointed to fuel delivery and/or spark management.

THE FIX: Turns out there was a built in tap off on the battery cable (big red one) coming from the clamp. It powered the nascent fuel controller (the flat black 4" X 5" thing held by a bracket right near the throttle body-don't know about '93). The lead swaging of the clamp was full of lead oxide. A new cable fixed all our ills.

FYI: The "computer part for the ignition" was housed in a compartment which was a bulge. Half of this bulge was the back of the glove compartment and the other half reached into the engine bay. The firewall was bulged to accommodate it.

Hope tis helps.

Top
#4547967 - 10/19/17 08:03 AM Re: 1993 K1500 TBI stumbling/surging [Re: kc8adu]
Phishin Offline


Registered: 05/01/12
Posts: 2428
Loc: Indiana
Originally Posted By: kc8adu
this one is a classic failure.pcv system blocked caused the blowby to enter the tbi through the vent.
rots the fpr spring and drops fuel pressure.
the tbi baseplate passages plug with crud.
clean it up and rebuild the fpr first.
do not plug off the pcv!
fix it.
also make sure the sensor ground cluster at the water outlet is clean and tight.
these 2 things account for the lions share of problems.


I agree with this. My 1990 K1500 has the 350TBI....and this fixed many of my problems as well.

The PCV on these things really tends to plus in the TB. I'd go to NAPA and get a TB rebuild kit. Take the TB off, clean it all up, replace the FPR diaphram and all the seals and gaskets and make sure the PCV port is cleaned really well. This shouldn't take you too long, it's kind of fun because it's all so easy, and you'll know from now on you don't have a fuel problem.
_________________________
2018 Chevy Silerado 3500HD 6.0L Gas: Undecided
2010 Accord-LX K24: VSP 0w20/MaxLife 10w30 + LG BioTech HD
2014 CR-V LX K24: M1 0w30

Top
#4547984 - 10/19/17 08:22 AM Re: 1993 K1500 TBI stumbling/surging [Re: BrianF]
kc8adu Offline


Registered: 08/02/05
Posts: 894
Loc: dayton oh
hopefully all the kits have the spring now.
many in the past did not.most common failure part and not in the kit.stupid.

Top
#4548002 - 10/19/17 08:39 AM Re: 1993 K1500 TBI stumbling/surging [Re: kc8adu]
Phishin Offline


Registered: 05/01/12
Posts: 2428
Loc: Indiana
Originally Posted By: kc8adu
hopefully all the kits have the spring now.
many in the past did not.most common failure part and not in the kit.stupid.


Mine didn't have a spring...this was the kit from Napa about 4-5 years ago.

I cleaned up the spring the best I could. I then put some light grease on it to prevent it from rusting. Since the spring "might" have been "tired" and lost some of it's function, I put a single US $0.25 Quarter in the throttle body to act as a spacer for the spring to give it a bit more force onto the FPR.
_________________________
2018 Chevy Silerado 3500HD 6.0L Gas: Undecided
2010 Accord-LX K24: VSP 0w20/MaxLife 10w30 + LG BioTech HD
2014 CR-V LX K24: M1 0w30

Top
#4548561 - 10/19/17 06:17 PM Re: 1993 K1500 TBI stumbling/surging [Re: BrianF]
kc8adu Offline


Registered: 08/02/05
Posts: 894
Loc: dayton oh
the $0.25 mod is a common way to boost fuel pressure a bit.
as for the spring most are in at least 2 pieces when i see them.the blowby backing up due to no vacuum on pcv blows right on it and rots it fast.
drive too long like this and the engine will sludge up.

Top
#4551662 - 10/23/17 06:35 AM Re: 1993 K1500 TBI stumbling/surging [Re: kc8adu]
Phishin Offline


Registered: 05/01/12
Posts: 2428
Loc: Indiana
Originally Posted By: kc8adu
the $0.25 mod is a common way to boost fuel pressure a bit.
as for the spring most are in at least 2 pieces when i see them.the blowby backing up due to no vacuum on pcv blows right on it and rots it fast.
drive too long like this and the engine will sludge up.


kc8adu: No doubt. When I bought my truck, it was a sludge MONSTER. I took the VC's off and scooped the crusty nasty crud out. Several times I filled the engine with kerosene and sometimes a mix of kerosene and toluene, disconnected the dizzy cap and would would crank it over for 15-20 second burst several times through out the day for several days. Drain and refill.

I bought my K1500 with 150k miles for $1800. I've put over 60k miles on her. She's still running decent.
_________________________
2018 Chevy Silerado 3500HD 6.0L Gas: Undecided
2010 Accord-LX K24: VSP 0w20/MaxLife 10w30 + LG BioTech HD
2014 CR-V LX K24: M1 0w30

Top
Page 1 of 2 1 2 >