Sy won't start...thoughts?

msheller

msheller

New member
truck was running great then quit all of a sudden.

fuel and injector tests ok. spark test all ok

WILL NOT START

Compression test as follows on 55k motor (w/pte52,50#ers, pl chip, etc),:
1-75
2-70
3-75
4-75
5-85
6-70

cam gear? timing chain jump time?? thoughts?

Thanks
 
msheller

msheller

New member
Re: Sy won't start...thoughts?

WyoSyclone said:
That's really low compression... should be up around 150.
Click to expand...

If timing's a tooth off couldnt valves fail to seal until the piston's already part way up...or something...and end up with "half compression" across the board?

has anyone else jumped time w/ syty's?
 
MRKING

MRKING

New Parts for Old Trucks
Re: Sy won't start...thoughts?

my compression check last week revealed 170's across the board .do you hear any noises ?
 
T

turboj91

New member
Re: Sy won't start...thoughts?

Can we assume that when the compression test was preformed, the throttle was W O and all the plugs were out?
 
sly dvl

sly dvl

Ya, it's got a Turbo
Re: Sy won't start...thoughts?

msheller said:
Compression test as follows on 55k motor (w/pte52,50#ers, pl chip, etc),:
1-75
2-70
3-75
4-75
5-85
6-70
Click to expand...

Redo the compression test with the fuel system disabled, the throttle pinned wide open, the battery fully charged and all the plugs out. If those readings are correct, there's your problem. With less than 1/2 of the compression that you should have there's no way that truck will start.
You need to find out why those readings are so low. Something mechanical has gone wrong.
You may also want to add a squirt of oil into each cylinder before the test. It's possible that the cylinders are "washed" with fuel, which will really lower your compression. How does your oil smell? Raw fuel smell?
 
Last edited:
msheller

msheller

New member
Re: Sy won't start...thoughts?

Jimmy said:
IMO that is the 2nd thing to check on a no start. 1st is hearing the fuel pump prime.

Fuel pump not priming first check is ECM-B fuse.
Click to expand...

Ecm b ok, both pumps priming fine, tach jumps fine in cranking.... thoughts?

Is the oem cam gear part plastic?

Matt
 
msheller

msheller

New member
Re: Sy won't start...thoughts?

sly dvl said:
Redo the compression test with the fuel system disabled, the throttle pinned wide open, the battery fully charged and all the plugs out. If those readings are correct, there's your problem. With less than 1/2 of the compression that you should have there's no way that truck will start.
You need to find out why those readings are so low. Something mechanical has gone wrong.
You may also want to add a squirt of oil into each cylinder before the test. It's possible that the cylinders are "washed" with fuel, which will really lower your compression. How does your oil smell? Raw fuel smell?
Click to expand...

Will check....thanks for the ideas

Matt
 
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