K5 Blazer Forums  
Home of the 1969-91 K5 Blazer/Jimmy including GM Trucks and Suburbans.  
Go Back   CK5 Forums > General Discussion > The Garage

Remove these ads.

Reply
 
Thread Tools Display Modes
Old 10-08-2013, 09:36 AM   #1
EXJAY
Registered User
 
Join Date: Sep 2013
Location: Myrtle Beach, SC
Posts: 102

i Trader: (0 )

'88 TBI no start

Just got my father-in-laws '88 K5 (5.7 350) and was told it had fuel pump/no starting problems which is why he let it sit for a year. He originally told me the fuel pump would not prime when in "key on" position but when I got it towed to my place and started to look into it I can hear the pump prime now (maybe the tow and fuel sloshing around did something). SO... I've been researching/reading up on this issue and could be several things going on/causing no fuel to spray in the TBI. Just look to see wheres the best place to start in troubleshooting and looking for some input/suggestions. Here's what I came up with as the best logical order to start:

Check pump relay for proper operating/voltage in "on" and "crank" positions (I know its getting power (good fuse) since i hear it prime) but is it possible that one side of the relay will power the pump to prime but when it switches over for the ECM to take over in the cranking/run position that side of the relay could be bad?

Noid light to check pulse at injectors while cranking (if OK the ECM is good?)

Check for proper fuel line pressure at prime and crank (if OK this should also confirm that the relay and pump are good?)

if pressure is still "0" while performing fuel line pressure test I can assume the pump is bad? Fuel filter was recently swapped out and new battery installed btw.
EXJAY is offline   Reply With Quote
Sponsored Links



Remove these ads.
Old 10-08-2013, 10:27 AM
Posted in reply to EXJAY's post "'88 TBI no start"
  #2
dyeager535
Supporting Member
Registered User
 
dyeager535's Avatar
 
Join Date: Dec 2000
Location: Roy WA
Posts: 24,816

i Trader: (6 )

Forget the relay. It works if it primes, not the issue.

Noid light is where I'd start. Checking pressure on these is tough, but may be necessary later. However, if no injector pulse, fuel pressure isn't going to matter anyway.

It sounds like you want to verify the ECM is ok, which is a bad way to bias your thinking. The ECM is normally the LAST thing to suspect. Statistically, it is far more likely to be anything else, which is a fair number of things in a crank no start situation.
__________________
Dorian
web page
parts for sale
"1985" K5: Vortec Headed Roller 355/MAF TPI/32 spline 465/205/10B-14SF/3.42's/33". Will be converted to MAP TPI in the future.

1987 K5: 350/TBI/700R4/208/10B F/R/3.73's/31" Someday will assimilate the "1985" drivetrain.

The answer to your carburetor problem is fuel injection.
dyeager535 is online now   Reply With Quote
Old 10-08-2013, 10:47 AM
Posted in reply to dyeager535's post starting "Forget the relay. It works if it..."
  #3
mr.smartass
Supporting Member
Registered User
 
mr.smartass's Avatar
 
Join Date: Aug 2004
Location: Hattiesburg, MS
Posts: 10,842

i Trader: (7 )

I had the same issue on my 89, could hear the pump running in the tank but no fuel when I disconnected the line at the filter, dropped the tank and the little 1 or 2 inch piece of rubber tube connecting the pump to the sender had crumbled and fallen apart, pump was just spitting fuel around in the tank. Might have been from sitting in ethanol gas or just from being 24 years old. Something to think about.
__________________


Justin

'89 K5 Blazer, 350/700r4/NP241, 4" Spring Lift, 3" Body Lift, 37" PJ's, D44/14BFF, 5.13's


Come play with us!
mr.smartass is offline   Reply With Quote
Old 10-08-2013, 01:53 PM
Posted in reply to mr.smartass's post starting "I had the same issue on my 89, could..."
  #4
EXJAY
Registered User
 
Join Date: Sep 2013
Location: Myrtle Beach, SC
Posts: 102

i Trader: (0 )

Thanks. Was hoping to rule out everything before having to remove the tank for a pump inspection/swap (its 3/4 full). Did pick up a noid light test set from AutoZone (loaner tool program) and will report the results this evening.
EXJAY is offline   Reply With Quote
Old 10-08-2013, 02:14 PM
Posted in reply to mr.smartass's post starting "I had the same issue on my 89, could..."
  #5
rampage
Registered User
 
Join Date: Mar 2001
Location: South of SF,CA
Posts: 1,678

i Trader: (0 )

Quote:
Originally Posted by mr.smartass View Post
.... the little 1 or 2 inch piece of rubber tube connecting the pump to the sender had crumbled and fallen apart, pump was just spitting fuel around in the tank ...
Easy enough to check this. Disconnect fuel filter and connect a hose to a container to catch any fuel. Disconnect the wire harness at the fuel tank and connect 12V to the gray wire that goes to the tank and the pump should start spewing out gas (of course you need to connect ground to something suitable like the frame).
If gas does come out then I'd empty the tank and put in fresh gas. Gas that old won't help matters when trying to figure out why it's not starting.
rampage is offline   Reply With Quote
Old 10-08-2013, 06:21 PM
Posted in reply to rampage's post starting "Easy enough to check this. Disconnect..."
  #6
eagle mark
CK5 Staff
 
eagle mark's Avatar
 
Join Date: Nov 2004
Location: North Idaho!
Posts: 3,289

i Trader: (1 )

Actually easier then that. Hook 12 volt to red wire hanging from fuel pump relay. It has a clip on the end and is called a prime wire.

Does the vehicle have spark? No spark = no DRP Distributor Reference Pulse and fuel pump will not turn on after prime.
__________________
1990 Chevy Suburban 5.7L TBI ECM 1227747 HiWay Lean Cruise!
1998 Chevy Silverado 5.7L Vortec RoadRunner Lean Cruise!
CK5 Injection Section
GearHead-EFI.com
eagle mark is offline   Reply With Quote
Old 10-08-2013, 06:43 PM
Posted in reply to eagle mark's post starting "Actually easier then that. Hook 12 volt..."
  #7
EXJAY
Registered User
 
Join Date: Sep 2013
Location: Myrtle Beach, SC
Posts: 102

i Trader: (0 )

Only had a short time this evening to mess with the K5. Verified with the noid tester I do have pulse at both injectors when cranking. Also for the hell of it I bench tested the pump relay and it is also good. I will have to check spark tomorrow to be 100% sure and report my findings but was told durring my Father-in-laws attempt to troubleshoot back after it first stopped running that there was spark. I rather just start from scratch in troubleshooting and not assume anything. Thanks guys!
EXJAY is offline   Reply With Quote
Old 10-08-2013, 07:11 PM
Posted in reply to EXJAY's post starting "Only had a short time this evening to..."
  #8
4xcrazy
Supporting Member
Registered User
 
4xcrazy's Avatar
 
Join Date: Oct 2003
Location: Olympia/Lacey, Washington
Posts: 9,171

i Trader: (5 )

Shoot a couple of quick shots of ether down the intake, if it has any spark, it will ignite and try to start.
__________________
T.J.
4xcrazy is offline   Reply With Quote
Old 10-08-2013, 07:28 PM
Posted in reply to 4xcrazy's post starting "Shoot a couple of quick shots of ether..."
  #9
eagle mark
CK5 Staff
 
eagle mark's Avatar
 
Join Date: Nov 2004
Location: North Idaho!
Posts: 3,289

i Trader: (1 )

He verified he has spark with noid light firing injectors.

If he has good spark! I even tried the either trick last week and no go...

I just went through this on my sons 1988 Chevy TBI truck. Would not start cold. Had spark but I noticed the color was yellow? So me being an old guy knew that meant the points needed adjusting or replaced!

D'oh! No points? So I got the GM diagnostic tests for the coil and sure enough it failed two of the three tests. Replaced coil and it runs like a top!

Also checked spark once again with new coil and it was Blue. Much stronger and even had the audible SNAP when firing!

We had issues with this truck earlier in year and found the button in distributor cap was just hanging there, no spring load, lots of black traces from misfires all over rotor. So replaced cap and rotor and it ran... but still had an issue... in checking the EST module in distributor it had a melted plug! Probably from the bad cap rotor button. So we pulled distributor to replace the pickup coil which was also fried! This got most issues fixed but still not quite right? Till the coil replacement.

Seems the rotor button failure throwing 40k spark all over just fried everything! Truck has been daily driving no issues for a week... fuel mileage is way up. Amazing how these things will run even with faulty parts...
__________________
1990 Chevy Suburban 5.7L TBI ECM 1227747 HiWay Lean Cruise!
1998 Chevy Silverado 5.7L Vortec RoadRunner Lean Cruise!
CK5 Injection Section
GearHead-EFI.com
eagle mark is offline   Reply With Quote
Old 10-09-2013, 04:51 AM
Posted in reply to eagle mark's post starting "He verified he has spark with noid..."
  #10
EXJAY
Registered User
 
Join Date: Sep 2013
Location: Myrtle Beach, SC
Posts: 102

i Trader: (0 )

So if the ECM is sending pulse signals to the injectors it must be seeing fuel pressure at the TBI correct? Just trying to verify that the pump is working/doing what it should before moving on to troubleshooting an ignition issue. Thanks
EXJAY is offline   Reply With Quote
Reply


Currently Active Users Viewing This Thread: 1 (0 members and 1 guests)
 
Thread Tools
Display Modes

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

Forum Jump


All times are GMT -7. The time now is 06:26 PM.


Powered by vBulletin® Version 3.8.1
Copyright ©2000 - 2014, Jelsoft Enterprises Ltd.