wont start hot

[movieguy73]

94 ex wont start hot.
i drive a mail route and after 4-5 hrs driving a new rt wouldnt start after shutting it off to deliver a package.
cranks fine im guessing no spark.
new puter and fuel pump.

 

[MrShorty]

cranks fine im guessing no spark.

Time to stop guessing and check. I prefer to use my old inductive timing light to check for spark.

One thing I often thing of with a hard/no warm start is a bad FPR. Next time, remove the vacuum line from the FPR and look for gasoline. Any gasoline in this vacuum line=bad FPR (effectively, the engine is "flooded" in this scenario).

 

[movieguy73]

no way to check the spark other wise i would have.
fuel reg should be good.
new fuel pump 30psi with and 40psi with out reg vac line attached.
new fuel filter, new water pump.thermostat.

 

[MrShorty]

Without a timing light, I usually pull a spark plug, hook it up to the wire (or use an old plug that I have lying around), and "hold" the end of the electrode the the exhaust manifold/cylinder head and watch for spark. The tricky thing with this method is that you run the risk if you hold it wrong of having that "spark" go through you. Not really dangerous, but it is uncomfortable.

Were those fuel pressures tested when it wouldn't start?

 

[movieguy73]

ya i dont want to fry the computer by testing the spark against the block.
ive got a spark tester to use the next time it does it.
the problem is that theres no way to test it as its got to be driven around town for 4-5 hrs b4 anything goes wrong so its imposable to recreate.
and the shop cant run a scan on the puter.
its got a new fuel pump now so im sure its not the fuel system.
most intermittent not starting hot problems are usually electrical.

 

[KobeJ05]

coil pack?

 

[MrShorty]

When it won't start, does the CEL come on KOEO? One thing I hear of on these forums is relays that get hot and fail open. The CEL comes on KOEO to indicate that the PCM is getting power. The fuel pump relay has been known to do the same thing, which is part of why I asked if those pressures were tested when it wouldn't start.

 

[movieguy73]

i cant do any tests when it wont start.
cus i cant recreate the no start condition.
i swapped a few relays b4.
i think the coil pack tested ok my meters scale is screwy.
all 3 readings were the same so i think its ok.
i could hear the fuel pump running so the relay has to be working.
im guessing a relay can be closed but still open if the internal contacts are dirty.
its still in the shop so i cant do much checking this weekend.
if he cant get something figured out ill bring some tools along the next time i do that route to check for spark.
i dont recall the condition of the CEL.
im sure it was on KOEO
i cant rem if it turned off while cranking tho.
ive had this truck a few months but on this big route is the first time its not started.
icm tested good.

how does the iac work?
is it a solenoid?
when i turned the key on it stopped 1/2 way out for a ms.
then went all the way out.

 

[movieguy73]

bump