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Discussion Starter #1
workin on this unit for a friend. Will not start. This is what has been done started out with air filter hangin half open. Dirt all in throttle body. Did have it started once and now it Haden’s since then. New starter clutch new fuel pump.tank cleaned injectors fuel rail and map sensor. . Now it’s back pressuring outa throttle body. Out of time? Getting CPS code. Will it being bad throw it outa time and cause this. Any ideas?
 

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Dirt in throttle body is not a good sign. It's likely you have more issues than just backfiring through the throttle body. Perform a cylinder leak down test to confirm ring and valve seal. Engines with low compression are difficult to start if they start at all.

Backfiring through throttle body possible causes, not necessarily in order (note, some of these will cause low compression [marked with *]):
Possible ECU failure
Component failure causing ignition timing to be advanced (sensor, flywheel etc.)
Sticking exhaust valves *
Broken or weak exhaust valve spring*
Exhaust valve clearance too tight*
Damaged exhaust valve (burnt, bent, broken)*
Cam timing off (jumped timing chain)*
Cam chain too loose due to wear or hydraulic tensioner failure*
Cam chain broken w/ exhaust valve in open position*
Bad spark plug
 

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And just to add; no/low fuel pressure (lean fuel mixture)
 

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How can I check timing chain to see if it’s jumped.
Get a digital Service Manual, about $10 on line. A search of this site will provide information about where to obtain one if someone else doesn't jump in with info.
Checking valve timing requires valve cover removal.
Everyone has different ideas, however, were I in your shoes I'd do a cylinder leak down test first. Results will tell you whether an overhaul is in order, if any valves are leaking and which valves (intake or exhaust). If you need to perform an overhaul you'll find any valve timing problems during tear down/inspection, as well as broken valve springs, sticking valves, bad valve guides, worn/broken tensioners, etc.

If you're going to work on your ranger you will need the Service Manual.
 

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I would proceed with the leak down testing or AT LEAST a compression test to see if the engine has been 'killed' and then figure out why you have the CPS code as it will not start with a CPS snafu.
 

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Not good if it got dusted.
as stated a couple times. Compression test I’m sure that’ll show you the problem.
 

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Discussion Starter #10
after further looking found cam chain stretched and cam gears bad from it slipping. Tensioner all the way out.
130874
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Discussion Starter #11
Have read where this Is a common problem. Also seen where some are putting after market tensioners. What’s the best out there?
 

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The '18 model 900's use a ratcheting type manual tensioner. There isn't an aftermarket for it that I know of. The Alba ones are for the earlier model cylinder.
Those chains don't stretch, they wear out.
I would check that motor over pretty good for wear.
 

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Discussion Starter #16
The '18 model 900's use a ratcheting type manual tensioner. There isn't an aftermarket for it that I know of. The Alba ones are for the earlier model cylinder.
Those chains don't stretch, they wear out.
I would check that motor over pretty good for wear.
Where would one look for wear marks? Are there some measurements to go bye that will tell you to replace?
 

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Yeah....ALBA
The '18 model 900's use a ratcheting type manual tensioner. There isn't an aftermarket for it that I know of. The Alba ones are for the earlier model cylinder.
Those chains don't stretch, they wear out.
I would check that motor over pretty good for wear.
Good catch Rock !
 

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