Just to say it out loud... Iirc, timing for TBI motors should be set / checked with a connector in the engine compartment (close to the main harness plug) disconnected.
CK5
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- Thread starter JOES89K5
- Start date
New ignition cylinder was put in a month ago could
But not ignition switch should that have been done?
Plugs look good
Timing set at 0 by Dyno shop
I could go back to make sure
The owner at the shop had one 88’ Blazer and seems to be knowledgeable.
But not ignition switch should that have been done?
Plugs look good
Timing set at 0 by Dyno shop
I could go back to make sure
The owner at the shop had one 88’ Blazer and seems to be knowledgeable.
Kain
3/4 ton status
is there a way to see if it has any codes
When it long cranks is it after parked for along time or just a few minutes? Have you noticed a pattern?
no pattern cold, hot, driven, sat a few days
JOES89K5
1/2 ton status
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Hello When I did my timing after pulling intake manifold off Several times I did the number one piston top dead center and faced the distributor in the direction the dealer manual indicated. I figured I give it a try. I know theres your basic way of this done and different strategies on this topic but this one worked for me. I then checked it with timing light and it was pretty much correct on. I was surprised it worked. I guess you really need to get number one piston positioned correctly.
Ok so my first guess, swag system, is the IAC motor may not be positioning correct for start up. Cracking the throttle may help.
My 2nd area of suspicion is fuel pump/filter, pump relay. When pumps get worn they sometimes don't turn on. Has it ever quit while driving?
When you turn the key to on position, the computer will run the pump for 2 seconds. After engine starts the oil pressure switch will power the fuel pump relay.
So if the computer doesn't run the pump for the prime, you would need to crank until oil pressure built up to power relay.
There may be a sloppy connection between the the control side of relay and the computer. Probably wouldn't set a code.
Make sure all of your grounds from battery to frame engine and fire wall are nice clean and solid.
Put a volt meter across your battery and see what voltage drops to when cranking. If it drops much below 10v the computer will have a tough time doing everything it needs to.
See what happens and let us know
My 2nd area of suspicion is fuel pump/filter, pump relay. When pumps get worn they sometimes don't turn on. Has it ever quit while driving?
When you turn the key to on position, the computer will run the pump for 2 seconds. After engine starts the oil pressure switch will power the fuel pump relay.
So if the computer doesn't run the pump for the prime, you would need to crank until oil pressure built up to power relay.
There may be a sloppy connection between the the control side of relay and the computer. Probably wouldn't set a code.
Make sure all of your grounds from battery to frame engine and fire wall are nice clean and solid.
Put a volt meter across your battery and see what voltage drops to when cranking. If it drops much below 10v the computer will have a tough time doing everything it needs to.
See what happens and let us know
Gonna give it a check tomorrow
Gotta take my 4YO and get some exercise before she spins.
I will do all listed above
Thank all of you for your knowledge
Gotta take my 4YO and get some exercise before she spins.
I will do all listed above
Thank all of you for your knowledge
If you can find it, you can disconnect the oil pressure switch (should be two wire connector, near distributor?) and drive as normal. If at any point it simply cranks and won't start, you've probably pinpointed the fuel pump relay as the issue. Note that you should always hear the pump run for a few seconds when you turn the key to run (not start) as long as there is a few seconds between the key being cycled to run. Should be pretty simple to listen for that before trying to start. The ECM controls that prime cycle via the relay.
The red wire dangling off the fuel pump relay connector is a test lead, 12v+ from the battery will force the pump to run, so another mechanism to check relay failure with the pressure switch disconnected.
I *think* the TBI trucks use the same style relay for AC and fuel? You could also swap those (or just the connectors if close enough) and see if the issue with fuel goes away.
The red wire dangling off the fuel pump relay connector is a test lead, 12v+ from the battery will force the pump to run, so another mechanism to check relay failure with the pressure switch disconnected.
I *think* the TBI trucks use the same style relay for AC and fuel? You could also swap those (or just the connectors if close enough) and see if the issue with fuel goes away.
Excellent Info, I was not able to work on My truck today but this week when the kiddo is in school I will get to it.
With all the advice/suggestions I should be able to pinpoint it. Gonna write down all the info and go through each suggestion
Thank You nvrenuf, kain, wes harden and dyeager535
thanks
So far this is where i'm at got a few more things to check on the list
coil check
New Pos and Neg Cables all ground wires check
timing set at 2BTDC check
IAC check
fuel pump relay check
fuel pressure 7.5psi seems low could this be the problem?
Spark plugs AC Delco CR43TS gapped at .040
I Was running two bottles of techron through the system right before I took the plugs out(brown color)?
coil check
New Pos and Neg Cables all ground wires check
timing set at 2BTDC check
IAC check
fuel pump relay check
fuel pressure 7.5psi seems low could this be the problem?
Spark plugs AC Delco CR43TS gapped at .040
I Was running two bottles of techron through the system right before I took the plugs out(brown color)?
7.5 psi is low iirc the spec is 12 to 14psi.
Got to pull the tank right?
Ac delco or Delphi
Ac delco or Delphi
yes pump is in the tank. Change your fuel filter 1st and retest. then go after pump if not in spec. I don't know if either brand is better then the other. Both made in china now.
Thank you
I'll get to it this weekend appreciate the help
I'll get to it this weekend appreciate the help
If forgot to mention the fuel pressure regulator, the spring may be weak or broken, this will cause low fuel pressure also. The pressure regulator is the round can on the throttle body. I believe a rebuild kit for regulator is less than $30 these days.
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Bought an ac delco made in brazil pump EP386 and filter couldn't find any made in usa. gonna put it in this next week, hope this fixes it, if not it was needed anyway
Put in New filter, pump, Coil, Plug wires.
Runs smooth idles smooth but still occasionally takes an extra second to fire up. Might just be cause im comparing to My 2012 Tahoe?
Bigger issue according to my plugs
If the deposits are on one side of the plug, this is an indication of upper engine wear valves, seals, cylinder head
Runs smooth idles smooth but still occasionally takes an extra second to fire up. Might just be cause im comparing to My 2012 Tahoe?
Bigger issue according to my plugs
If the deposits are on one side of the plug, this is an indication of upper engine wear valves, seals, cylinder head
