Contrary hard starter

[randel1@comcast.net]

Hello all, this is my first time on so I hope I am doing it right.
I have a problem with a SX200TXRB. It is very difficult to start when it has sat and cooled down. The starter isn't dragging and the solenoid is making good contact so I have eliminated those as a problem. If I pull the intake cover and squirt some gas into the intakes it will start right up. Or if I pull the plugs and squirt some fuel into the cyl's. it again starts easily. After I get it started it will re start easily, less than 1 rev. of the crankshaft. Let it sit a few hrs. and cool down and I have to physically prime it to get it started. It is a fresh rebuild and compression is 130 +/- 5 PSI all cyls. Also it was difficult to start prior to the rebuild. I would appreciate any ideas or tips. Also the O2 sensor checks out and is squeaky clean.
Thanks ahead of time.

[rodbolt17]

I cant say cause your clueless, that may get me in trouble.

I can say you have no idea why or what happens when you hit the key.

let me break it down a bit.

at key ON, the fuel pump runs about 3 seconds to prime the rail at roughly 35 PSI, does this happen??????

at START the ECU looks at the CTS and the start signal and locks the system in for cold or warm restart.
does this happen?????

once started after about 5 seconds the ECU is looking at pulser coil inputs and CTS inputs .

NOTICE it is NOT looking for O2 sensor inputs.

at cold start and until the CTS tells the ECU its above 113*F the O2 sensor is out of the picture.

see how easy this is?????

all ya gotta do is spend about 5000 dollars on training.
about 400 dollars on some basic test equipment .
then look at how its supposed to work.
whats missing.
why wont it work.

its that easy.

first thing, whats the rail pressure at key ON engine off.

[CatCam]

now now Rodbolt - be nice -- newbie on his 1st post hahaha!!!

Randel1 - Yep, take the tech advice from Rod - he knows his stuff about these motors!

Reply back with the rail pressure......

[TownsendsFJR1300]

CTS is cold temperature sensor BTW.

Basically telling if the engine is still cold and to enrichen the mix

[rodbolt17]

the OX66 will pretty much trouble shoot itself if you pay attention.

the O2 sensor is NOT monitored for faults other than is it plugged in.
NO codes for O2 sensor failure or if its unplugged.
O2 sensor feedback is not used until the ECU sees an engine temp above 113*F.

if engine cranking speed is below about 350 RPM it will be hard to start.
if the ECU,fuel pumps and injectors cannot maintain 10.5V min at cranking it may or may not start.

if ANY sensor fails or is out of range,other than the previously noted O2 sensor, the ign timing defaults to a base timing of 7*BTDC, simply wont retard any further.
DEPENDING on the sensor it may or may not advance and the motor may or may not reach WOT.

its a pretty simple speed density EFI setup similar to a lot of automotive stuff that can run in open or closed loop.
all the O2 sensor does is trim the fuel delivery by constantly monitoring the amount of oxygen in the ex.

typically hard starting is fuel related or bad battery cable/connection.

but without doing actual voltage output tests the O2 sensor cannot be verified nor any other sensor.

there is a lot of good reading on the theory behind speed/density EFI and what all the sensor do.
google can be your friend,wish it was avalible 35 yrs or so ago when I had blond hair.

[randel1@comcast.net]

Thanks for the feedback. The rail pressure is at 38 PSI with ignition on and pump running. When the pump kicks off the pressure gradually drops to about 32 PSI. The CTS resistance tracks as per specs. with temp variation. Also the harness rang out so the connections are Ok.

[randel1@comcast.net]

I think I found the problem. I checked the voltage at the starter while cranking and it seemed a bit low. Not so at the battery. Also the voltage on the fuel pump was down around 8 VDC while cranking. I traced the problem back to the perco switch. It was not showing evidence of heat build up but the external connections were corroded but tight and the internal wiper may be resistive also so I tossed it and hooked directly to the battery. The motor started right up. At 70 I don't hear so well even with two hearing aids but the starter seemed to be spinning the motor ok.
Yes, on some thing I am clueless that's why I ask questions.
If you ever have a problem starting your F-4, C-5, C-131, Hawk missile or Atlas rocket I can probably help and will do so without snide remarks.
Thanks for the help Rodnut.

[99yam40]

Your original post said the starter was not dragging so you eliminated that or bad connections. I assumed you tested things to do that.
I started to mention not to eliminate anything until you make sure by testing, but I held off.
Rod posted a lot of things to be checking and the slow turning/ low voltage was the problem seems like.
Hard to troubleshoot from a computer screen far away from the motor
if no testing and results are given.
Even the battery cables can go bad internally, so always test to eliminate.
Glad you found it quickly

[Reel Kahuna]

Funny you mentioned the Perko switch because I had the same problem on my F115 where the starter was dragging. Then I by-passed the Perko and fastened the cables directly to the battery and va va boom, the motor fired right up.
Decided to order a Blue Sea dual battery switch this time.

[boscoe99]

I think I found the problem. I checked the voltage at the starter while cranking and it seemed a bit low. Not so at the battery. Also the voltage on the fuel pump was down around 8 VDC while cranking. I traced the problem back to the perco switch. It was not showing evidence of heat build up but the external connections were corroded but tight and the internal wiper may be resistive also so I tossed it and hooked directly to the battery. The motor started right up. At 70 I don't hear so well even with two hearing aids but the starter seemed to be spinning the motor ok.
Yes, on some thing I am clueless that's why I ask questions.
If you ever have a problem starting your F-4, C-5, C-131, Hawk missile or Atlas rocket I can probably help and will do so without snide remarks.
Thanks for the help Rodnut.

Rodbolt/nut and snide remarks go together like love and marriage. Like salt and pepper. Like Frick and Frack. Like Yamaha and high prices.

[rodbolt17]

like sterndrives and curse words .
but I was right.

its ok though, I am used to that condition.

however a quick voltage drop test of the positive and negative cables would have found it in about 10 min or so.