95 Tahoe 4x4, ~5 sec of cranking before starting

[MotoCARR]

1995 Tahoe 4x4, ~205k.

Issue: The truck has to crank for about five seconds before it starts up. Once it starts and is running, motor drives fine. If I drive a bit, park for 5 min or so, and then try to start, it fires up like any other car. The longer it sits after driving the longer it takes to restart, but it never takes longer than about five seconds which can be seen in the video.

The air cleaner has been taken off and we watched the fuel injectors spray while the truck is running and it looks as if plenty of fuel is being sprayed, and I get about 12 mpg city driving which seems to be about normal. One thing to note is that the tubing that goes from the round aircleaner on top of the throttle body to the fender to help bring in air is missing, if that's even an issue worth mentioning. One thing to note that I have tried is turn the key to ignition and wait a few sec when a fuel pump typically would "prime" and then tried starting, same issue.

Thoughts on what the issue could be?

https://www.youtube.com/watch?v=UBTSXvPji1A&feature=player_embedded

 

[Boomer MN]

Watch your Oil pressure gauge. Does it fire when you get to about half of scale on the gauge? Do you hear the pump hum when you turn the Key to "on"?
It will start when it is hot as you still have gas in the log. Once it drains back, you are dependent on the pump to provide gas.
I believe there is circuit tied to Oil pressure. Look at the sending unit and see if it has 3 wires.
one is the reference, one is 12V, and the other is the Oil pressure interlock.

Boomer MN

 

[eg30.06]

How old is your fuel filter? When was your last tuneup? Plugs wires cap rotor etc?

 

[jrollings]

subscribed as my Burb is doing this as well.

 

[dowsewashere]

Mine does the same. Ive concluded my battery and fuel pump are just old. Yours sounds like the battery doesnt quite have the amperage to get the motor moving along quite fast enough/ a semi plugged fuel filter. Being if it sits too long mine does the same mainly because its cold, check the voltage across the battery if its sitting too

 

[someotherguy]

Many possible causes.

If it runs well after it starts, I wouldn't be too concerned about operating fuel pressure yet. However, the short piece of fuel line between the pump and sender's hard line could be deteriorating; this makes it tough for the pump to build initial pressure. Since this requires dropping the tank on your Tahoe...you can leave it for last.

As someone else asked what state of tune is the engine in? Old plugs, cap, rotor, wires can increase how long it takes to start.

Fuel pump relay could be bad, causing you to rely strictly on the oil pressure combo switch - when you've generated a small amount of oil pressure by cranking the engine, the switch closes and powers the fuel pump circuit as a backup in case the relay fails. Easy enough to try another relay.

Richard

 

[jrollings]

Is it possible to swap the relay with another one on these trucks to rule out a relay issue? noob question but Im new to gmt400s, been a f*** guy most my life.

 

[someotherguy]

1988-1994 use a unique relay that there isn't a spare one anywhere else on the truck. Not sure about a 1995 like OP's; if I recall the one-year-only 1995 engine harness does have an electrical center on the driver's side fenderwell that might have some similar relays that could be swapped as a test. Relays are cheap though...

Richard

 

[jrollings]

theyre cheap enough to buy @ $14 at your local autozone. I will probably go get one later myself. Can never hurt to have spare in the glovebox if it makes no change in starting like above

 

[jrollings]

Moto, any updates????