Slow 'lazy" start

[dave s]

Been chasing this gremlin since I got truck in November. Replaced fuel pump, rebuilt tbi and put on a CFM Technologies fuel gauge on to see pressure easily, replaced tps sensor, and fuel filter. I haven't licensed it but do run it back and forth from the house to garage repairing everything. About two months ago it would crank but not start. I saw it had fuel pressure so I checked spark. No spark. Replaced module, fires right up and all is well. Last night I go to put it away and it cranks but no fire. I try again and it sort of rolls into a running engine. Like usually it fires right up and idles a bit high for a few seconds and slowly lowers the idle. Well this sort of seems like it's cranking and barely firing then rolls into a full start and revs just fine, sounds good. Put it away, turned it off then tried starting and same slow lazy start issue. Cranks fast, just doesn't fire quickly like normal. I have good fuel pressure, looks like 12 psi. I'll try it again today but this "lazy start" needs to be figured out. I wouldn't trust this thing to drive anywhere as I'd be afraid it might not fire. It's a 94 with the 305 5 speed. I do have the ALDL cable but never found the right codes for my computer. It's an oddball. I'm not sure where to even start on this one.

 

[someotherguy]

Tough one.. check the wiring to the module for cracks/brittleness.

How many miles on the engine (particularly the distributor) ?

Richard

 

[Erik the Awful]

What's your timing set at? How fresh are your plugs?

 

[dave s]

Tough one.. check the wiring to the module for cracks/brittleness.

How many miles on the engine (particularly the distributor) ?

Richard

Engine has about 145k, normally hit the key and strong quick start. Not sure if it has any relevance but I had both doors open for a couple hours and interior lights on. Now the engine spun over just as fast as normal but it had the lazy start. After I drove it up to the garage, a couple hundred yards away, I turned it off and tried the restart. Took awhile and still slow to start. Went up in the morning, fired off like a new truck.

 

[dave s]

What's your timing set at? How fresh are your plugs?

Plugs are new. I honestly have never checked the timing. I'll give that a go when we get back.

 

[PlayingWithTBI]

Check your TPS too, if the PCM sees an open throttle, it'll think you're in flooded mode and won't give it any gas.

I do have the ALDL cable but never found the right codes for my computer.

95 was a transitional year but, you should have the 7427 PCM (most common).
https://xtronics.com/wiki/GM_ECU_eproms.html

With TunerPro RT v5x, your xdf mask s/b $4D while your adx definition file s/b A217 $0D TP5 v250. If those don't work, try $0F
Here's a link to what you should need
http://www.gearhead-efi.com/gearhead-efi/def/

 

[Schurkey]

1. Do you have fuel spray from the injector during the "long crank"? No fuel spray could be a failed fuel pump relay, failed ECM or failed wire harness. Engine has to crank long enough to build oil pressure, then fuel pump runs on power supplied by oil pressure switch. Another test that verifies the same problem: Does the fuel pump prime and provide proper pressure when key is turned from "Off" to "Run"? Most trucks have a two-second prime, some have a "Hot Fuel Module" that has a longer prime.

2. Last time I fixed this problem, it was a failed cap and rotor. The center button on the cap--that comes from the coil wire--was burnt to nothing.

3. If you actually had a failed ignition module, the ignition coil is suspect. The ignition coils partially-short; the coil is weak (weak spark) in extreme situations, and the current drawn by the coil increases due to lowered resistance. The increase in current is hard on the module, which cooks. Then you replace the faulty module (but not the coil) and the faulty coil burns up the "new" module.

Remember that an ohmmeter can tell you if a coil is BAD. It cannot tell you that the coil is GOOD. The voltage used by an ohmmeter is so low compared to the operating voltage inside an ignition coil, that the insulation may not break-down when tested by an ohmmeter. But when actually operating, the insulation on the wires may be faulty. There's pretty-much no substitute for a genuine spark-tester, calibrated for HEI ignition systems. Typically less than $15 on Amazon; although some folks are selling them for more than that. Shop around.