GM Truck Club Forum banner
1 - 8 of 8 Posts

·
Registered
Joined
·
3 Posts
Discussion Starter · #1 ·
Hi,

I'm trying to diagnose a non running condition on my 1995 GMC Suburban with the 454 TBI setup. It stopped running in my driveway this week. It has 101k miles so I replaced the fuel pump and have confirmed I have fuel pressure to the TBI unit. If I pour a little gas in the TBI unit the motor fires right up and then dies.

As we crank the engine I see no spray pattern from the injectors. I checked the injectors for voltage and each one does have 12v going to it but they do not pulse when cranking the motor.

What things should I check next? The motor ran fine before. It died as I was putting on a new air cleaner and I thought maybe the air cleaner shorted something as I laid it on the TBI unit?

Any help greatly appreciated. Thanks.

Jim
 

·
Registered
Joined
·
15 Posts
Hi,

I realize you are thinkin, fuel BUT... I had an instance with my 92 Suburban

I started the "burb" after work, let warm up about 30 seconds or so, and proceeded to drive away from work, about 2 blocks away traveling down the street, it simply "gave up the ghost" and I slowly coasted to a stop on the side of the road. I looked, lots of fuel, tried to start it again, nothing, (it cranked over but no start), had to tow it home....


After 5 hours of diagnosis...... Ignition coil simply "went bad", new coil, it fired right up!!

here's the thing.... poured gas down the TBI.... would start and die again right away.....


DON'T think yours is the same problem (with no gas from your TBI) but the sure seem close.......
 

·
Registered
Joined
·
112 Posts
I would say that you need to look into the computer to why it is not signaling the TBI to fire.

If you pour gas into the TBI and you fire, then you have spark, but you may have lost a ground connection that is not sending the connection back to the ECM.

You may want to start looking at the connections around the TBI and around, you may have skin'd a wire or pulled a wire out of a connector?

Could be a simple problem, or might be something that just gave up the ghost
 

·
Premium Member
Joined
·
1,625 Posts
Ignition modules will stop fuel to the injectors, and start when you prime the system, don’t ask me why they just will.
 

·
Registered
Joined
·
296 Posts
have you checked if it threw a code when it died?
 

·
Registered
Joined
·
3 Posts
Discussion Starter · #6 ·
Update

here's an update on my Suburban:

So far I've replaced the fuel pump and am getting 40# of fuel pressure at the TBI inlet, replaced the ignition module, and replaced the ECU. The motor fires briefly but then dies again. I get some spray pattern for a short period of a couple seconds and then it dies.

I've tried to clean all the grounds but have not been able to get to the one behind the head on the passenger side yet.

When I check for codes all it gives is the normal 12, 12, 12 and after the 2 the injectors click so I thik that is good?

I checked the oil pressure switch and get12v into it and 12 volts out when I crank it, the third wire on it does not do anything from what I can see.

The TPS unit voltages seem to check out also.

one item I am not sure of is the large round piece at the front right side of the throttle body. When I insert a test light into the injectors on the 12v side that unit clicks each time. I cannot seem to get any grounding from the other side of the injector at all.

Any other suggestions? is there a crank senor on the 95's? I can't see one.
 

·
Registered
Joined
·
3 Posts
Discussion Starter · #7 ·
Update #2

Here's another update. Tonight I switched the coil with a known good one but no change, still no injectors firing. Any other ideas?
 
1 - 8 of 8 Posts
Top