Intermittent starting issue when hot on new-to-me Cruiser (1 Viewer)

[arulataq]

So, I picked up a '97 with ~170,000 miles on the 29th of July and have driven nearly 3,000 trouble-free miles since. My full tank mileages have ranged from 13.1mpg to 16.1mpg, idle is around 600RPM, and the engine seems to have decent power and runs well.

In the last week I now seem to have begun seeing intermittent starting issues when the vehicle is hot.

I've had this problem twice, both times when trying to start the Cruiser in the late afternoon on 90+ degree days after having driven it on a number of trips of 5-20 minutes in the morning and early afternoon. I've attempted to reproduce this issue since the first time and was not successful until today (though, I wasn't actually trying today).

First occurrence (8/9/11 - 81* high, parked in sun):

• Parked Cruiser at ~4:15, tried to start at ~5:00. Turns over strongly, but does not start.
• Left alone for ~1 hour to search MUD and to run an errand
• Checked codes -> no codes or pending codes
• Checked fuses in driver's footwell and underhood -> no apparent issues
• Checked relays underhood -> no apparent issues
• Attempted start -> start OK

Second occurrence (8/13/11 - 89* high, parked in sun):

• Parked Cruiser at ~3:30, tried to start at ~4:40. Turns over strongly, but does not start.
• Put in different EFI relay (guessing as relay seems to be especially hot) -> no start
• Checked codes -> no codes or pending codes
• Checked fuses in driver's footwell and underhood -> no apparent issues
• Ran inside an pulled up "Emergency Start Troubleshooting procedures" from the FAQ -> started working through "Scenario 3"
• Check engine light is burned out, so is not visible one way or the other
• Pulled #1 spark plug, attempted start while holding spark plug against block -> no spark observed, no start
• Re-installed #1 spark plug and attempted start while listening for fuel pump -> no start and no fuel pump heard
• On a whim, pulled #1 spark plug and tested again with no apparent spark @ ~5:15-> start OK
• Shut down, re-installed #1 plug and associated wiring
• Attempt start @ 5:20 -> start ok

So, I'm a bit stumped.
The first situation took me by surprise with little in the way of tools with me, so is not a source of much information.
The second situation simply confused me more - no spark was apparent, but start was eventually successful. This start occurred before I could test for fuel and I saw no spark (though this may mean nothing), so no real information there (at least as far as I can tell).

Given the information above, does any one have any clue as to where I should be looking next? I don't want to completely shotgun this, replacing things without reason, but am really not sure where to look next as I can't necessarily reproduce the issue on demand. Any help would be much appreciated...

 

[Tools R Us]

My first check on a crank w/no fuel or spark is the fusible links. With age the wires can crack inside the insulation causing intermittent main power loss. My first test is to pull on them, if solid will not be able to pull them apart, if one or more separate, it (they) were broken.

 

[arulataq]

The fusible links seem good, but am replacing them just in case. I am currently awaiting their arrival.

On a related note, the vehicle had the issue for the 3rd time today.

Third occurance (8/16/11 - 80* high, parked in sun):

• Drove vehicle for ~15 mins and turned off at ~8:00AM.
• Attempted start at ~5:00PM, vehicle turns over strongly but no start.
• Opened hood and let sit for ~15 minutes.
• Attempted start and started nearly immediately with smell of gas.
• Ran normally for remainder of evening with multiple trips and restarts.

We should still have a number of days of decent heat in MT to try out the replacement fusible links, but I'm looking for additional low-cost potential culprits to replace simultaneously. This is a bit of a shotgun approach, but I'm looking to replace potential weak links on this 14 year old truck anyways, so am somewhat OK with this.

Does anyone have any other/additional suggestions?

 

[gtfour43]

So, I picked up a '97 with ~170,000 miles on the 29th of July and have driven nearly 3,000 trouble-free miles since

.

Damn you drive a LOT

What have you done to the vehicle since you got it? Any PM work done yet? Can you get a fuel pressure gauge that you can leave connected for a while? See if your getting pressure on the no start times. Are you sure you got no spark? Maybe borrow a spark tester from someone?
Does it idle fine or stumble when it eventually does start?

 

[SFSig]

Except for the the "no spark" thing it sounds really close to when my guzzi get's vapor lock. Sometimes when my bike gets hot it'll crank but won't turn over. Opening the gas cap releases the negative pressure built up in the tank and allows the pump to move fuel to the cylinders.

It's a long shot and I'm not that mechanical, but next time it happens see if there's an excess of negative pressure in your tank by opening the gas cap...

 

[Bastler]

1. If you have screw-down posts on your battery, make sure that all the wires attached are clean and secure - you could be getting 12V to your starter, but not enough to the rest of the vehicle to power everything else. Check the other end of the small wire off of the negative post, too.

2. Check spark at the coil - disconnect the coil wire from the distributor and hold it near a ground while cranking the engine. (don't crank too long, or you'll get a buildup of fuel in the intake/cylinders/exhaust)
IF NO SPARK AT COIL: Check for 12V at the + pin of the coil when the key is on. (The + pin is the one next to the clip on the connector that you removed to get to the pins.) Check the resistance across the + and - terminals, it should be 0.36-0.55 Ohm if cold, 0.45-0.65 Ohm if hot. Then check the resistance from the + to the output post, it should be 9-15.4 kOhm if cold, 11.4-18.1 kOhm if hot. If the coil checks out OK, check for loose connections or damaged wires in the harness attaching to the coil.
IF SPARK AT COIL: Check the resistance of your spark plug wires - should be no more than 25 kOhm. Pull the distributor cap and clean the bottom of the cap and the rotor with a CLEAN rag - even a small bit amount of residue could short the spark to ground. Look for cracks or damage. If they look good, reassemble and make sure everything is connected securely. There are some more checks you can do on the distributor if this doesn't help...

3. Check for fuel delivery - Crank the engine for 5 - 10 seconds, then promptly pull a spark plug or two and see if they are wet you can smell fuel. (This isn't very scientific, but you wanted cheap.) Alternatively, if you have a fuel pressure gauge handy, check for fuel pressure at the inlet to the injector rail - should be about 40psi.

Good luck.

 

[Layonnn]

This is my previous 80. All OEM Toyota parts bought from CDan/Beno,

Previous engine maintenance i have done was all between 160-165K miles in the last 6 months:
Radiator flush and fill with Toyota Red and distilled water, replaced all rubber hoses with OEM toyota for radiator hoses and NAPA green high temp silicone hose for PHH and other hoses.
Plugs, cap, rotor and wires all new OEM Toyota.
Front and rear O2 sensors, new OEM.
New air filter, NAPA.
Throttle body clean. (didn't remove, just opened flap and cleaned thoroughly)
Cleaned MAF
New Bosal OEM replacement cats and y-pipe (and flowmaster muffler then a glasspack)
Adjusted timing to 6-7* BTDC
Replaced grommet and positive crank case hose (i think that is what they are called, the two hoses that come off the top of the valve cover), new OEM Toyota.
Replaced air intake tube with a used one in better condition. (old one wasn't cracked, but it came with some other parts i bought from a parting out 80)

I had never had any issues like mentioned above with starting and it easily gets to be 100*-105* here throughout this summer.
I have not done anything with the fuel pump or fuel system at all other than occasionally adding Lucas fuel cleaner and running 89 octane gas.
Battery has new military terminals on it and is running a brand new Diehard Platinum.

 

[Layonnn]

Hey T, did the issue go away or did you find a solution/fix?!?

And lets see some pics of the Gobi if you got it on

 

[arulataq]

Thanks for replying with more info Layton!

Unfortunately, the issue hasn't gone away and I haven't found a solution (though, I may be a bit closer to a solution).

A couple of days ago I tried to start it after sitting in the sun and got the same symptoms (cranks hard but no start). Then I:

• Tested for spark with spark testing tool - no spark
• Tested for injector pulses with a noid light - no pulse/power
• Ran out of time and had to leave the truck alone for a few hours
• Attempted start upon return - started and ran/idled normally

Now, this makes me think its an electronics/ECM issue, but I'm afraid that I don't have much of an idea where to start tracking an issue like this down.

I have been out of town quite a bit, so haven't had a chance to investigate this much, but am looking to spend some time in the coming days trying to nail it down (and will follow Bastler's suggestions re:the coil).

Any thoughts?

 

[arulataq]

So, it's been a while since I've posted an update to this thread, so I thought I'd provide some info in case someone else runs into this issue in the future.

The no-start-but-strong-crank issue has persisted, happening whenever it gets quite hot out. I spent quite a lot of time tracing circuits while it was happening and found that the ECM wasn't receiving power when the issue occurred (verified with multimeter at the ECM and lack of CEL). I swapped out relays/fuses and traced wires looking for shorts, all to no avail.

Ultimately, I found the solution by chance. I was experiencing the issue this weekend and had swapped out one of the in-cab fuses. While applying pressure to seat the fuse, I turned the key to the "on" position and noticed the CEL was on. Upon releasing pressure on the fuse, the light went out. I'm able to consistently reproduce this and get the truck to start when it otherwise would not (pressure on the fuse box causes the CEL to come on and starting to occur). Additionally, as I was driving this evening I was running the heat on high and having it come out the floor vents when the truck died on me - shifting to neutral and attempting a restart failed, however, pushing on the fuse box allowed me to restart. This leads me to suspect that a connection is expanding under heat (such as a hot cab on a hot day) and needs to be redone.

I haven't taken the fuse box out to inspect connections and determine what is happening for sure, so I can't offer a definitive answer (I hopefully will soon, though), but wanted to get this info up in case it's of any use to others.

I'm curious as to whether anyone has experienced something similar or has any inkling of what's going on, as any info would be helpful before digging in to the panel.

 

[wearsabrowncoat]

I've never heard of this but it seems like it should be a fairly easy fix to get in there and bend the metal tabs to add some tension to the fuse holders.