97 LX450 Good spark, fuel and air and still no start (1 Viewer)

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Howdy to you all,

A little background on myself first. I am a 15yr professional mechanic mostly in heavy diesel and heavy truck and trailer. Just started to work in Moab, UT for a tour company that owns almost 20 of the 80/ LX450.

Now onto the problem at hand, I have a crank no start issue on a 97 LX450.

What I have checked so far:
Good spark on all 6 plugs
Good fuel pressure and good fuel to combustion chamber and air.
Plugs are wet with fuel when pulled.
MAF is showing proper OHMs for the temp outside
EFI fuse, ECM-IGN Fuse, ECM fuse is all good
EFI relay, fuel shut off relay are all new and good.
FPR is new and tests good.
Replaced ECM due to no voltage going to FPR from ECM pin for FPR. After replaced the FPR started working properly.
Bypassed RS3000 (no key fobs here)
Replaced fuel filter
Checked distributor for bad connections
Check engine light is on when key on and there are no codes in the system

I am going to replace the fuel pump for S&G's and the CPS.

Any help would be appreciated.

Thank you all.
 

flintknapper

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"Good spark, fuel and air and still no start"​


^^^^

That only leaves compression....so I'm going to say one of the above is NOT happening (sufficiently). Assuming you have compression.

Can you give us a little history on the vehicle? When was it last running, why are you working on it now (no start condition)?

What year model is it?
 
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Moab, UT
Forgive me ya all.

The starter works just fine. Engine turns over strong too.

This is a 1997 LX450. I am going after the CPS tomorrow.
 
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So here is the skinny on the unit. Unit ran fine last season all season long (march- November). Then it was parked for the off-season. Old mechanic was let go. I stepped in and went to start... dead battery. Changed battery and went to crank. Cranks strong and fast but no fire. Started my trouble shooting path from there.
 
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flintknapper

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I am under the impression that if the engine is cranking then the neutral safety switch is ok.

Agreed.

Fuel pump on these does NOT prime unless the engine is cranking, just in case you are not already aware.

Timing should be 3° BTDC (once you get it running).

If it has sat a long time without running DO check the compression. Sometimes the cylinders will have lost all of their residual oil coating and just get so much 'blow by' (past the rings) that there isn't enough compression. When testing pull ALL the spark plugs and hook up a battery charger to the battery so you have good spin over for each cylinder.

IF you show low compression, fog the cylinders with some oil/WD40/other and try it again. We've seen this happen before with a 1FZ-FE left sitting. Just something to consider and check off the list. You've done quite a bit already.

You might pull the cap on the distributor and take a pic of the rotor (position) and post it here. We can tell by looking if the timing is roughly correct (rotor position at TDC compression stroke on Cyl 1).

Dizzy Install3.jpg



It's possible the dizzy was pulled at some point and reinstalled 180 out.
 
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Olathe, KS, USA
Also possible rodent damage to wiring after sitting for 6 months.

Check air filter canister
Wiring harness for rodent damage
Check all 3 fusible links
Check crank position sensor

If plugs are wet, then either injectors are stuck open or no spark. Injectors open could point to wiring harness damage.

Check exhaust for rodent intrusion and clogging.
 
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Agreed.

Fuel pump on these does NOT prime unless the engine is cranking, just in case you are not already aware.

Timing should be 3° BTDC (once you get it running).

If it has sat a long time without running DO check the compression. Sometimes the cylinders will have lost all of their residual oil coating and just get so much 'blow by' (past the rings) that there isn't enough compression. When testing pull ALL the spark plugs and hook up a battery charger to the battery so you have good spin over for each cylinder.

IF you show low compression, fog the cylinders with some oil/WD40/other and try it again. We've seen this happen before with a 1FZ-FE left sitting. Just something to consider and check off the list. You've done quite a bit already.

You might pull the cap on the distributor and take a pic of the rotor (position) and post it here. We can tell by looking if the timing is roughly correct (rotor position at TDC compression stroke on Cyl 1).

View attachment 2643661


It's possible the dizzy was pulled at some point and reinstalled 180 out.
Roger that. Thank you.
 
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Oakland
Just a quick thought, also worth seeing if the throttle body is working properly. When these things sit they can get "sticky" it's easy to see if they're working properly by having the air intake boot off and seeing/videoing the butterfly valve in action. If anything else, might be worth a shot of starter fluid in there, too. Once you've diagnosed that the throttle body is working, throw the boot back on as the ecm needs the data from the maf to run properly.

Also second the cps check.
 
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UPDATE:
Checked timing- good
Checked for restricted intake and exhaust- no restrictions.
Checked for bad harness connections around the egr area- no bad connections.
Checked throttle body for sticky response or no response. No problems but I did notice that the inside of the intake is super dusted.

Performed compression test- all but one cylinder was under 50psi even with oil spayed inside.
1 cylinder has around 90psi.

So I am guessing that the valves are worn or sticking badly.

Manu manual says good compression is 170psi with a minimum of 128psi.


I think the head needs rebuilt unless you all have a quick fix solution?
 

flintknapper

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UPDATE:
Checked timing- good
Checked for restricted intake and exhaust- no restrictions.
Checked for bad harness connections around the egr area- no bad connections.
Checked throttle body for sticky response or no response. No problems but I did notice that the inside of the intake is super dusted.

Performed compression test- all but one cylinder was under 50psi even with oil spayed inside.
1 cylinder has around 90psi.

So I am guessing that the valves are worn or sticking badly.

Manu manual says good compression is 170psi with a minimum of 128psi.


I think the head needs rebuilt unless you all have a quick fix solution?


Leak down test might be your next best step, but I'd put some more oil down the cylinders, let sit overnight. Crank the next morning with plugs out (battery charger hooked up). Let the cylinders clear real well. Continue to crank intermittently until you're certain the piston rings are well lubricated and retest the cylinder pressures.

IF you still have low compression then pull the head examine cylinder bores and head.
 
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Leak down test might be your next best step, but I'd put some more oil down the cylinders, let sit overnight. Crank the next morning with plugs out (battery charger hooked up). Let the cylinders clear real well. Continue to crank intermittently until you're certain the piston rings are well lubricated and retest the cylinder pressures.

IF you still have low compression then pull the head examine cylinder bores and head.
How much oil is more oil?
 

flintknapper

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How much oil is more oil?
Couple of ounces per cylinder, enough to completely coat each piston top (so the oil is forced to drip off onto the sides), OR if you have a way to 'fog' the cylinders....all the better. The idea being we want to let the oil coat the cylinder walls (as much as they are exposed right now) AND seep down onto the rings overnight. We've seen this low compression thing before on engines that have sat. After cranking and lubing....a good number of them can be revived. But you don't want to crank DRY cylinders and rings ( I know you know).

IF that fails to bring up the compression, then you're looking at pulling the head to see what the trouble is .
 

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