Jona$
Master
My mcx Apex is very hard to start sometimes after its been standing for a 15min or so after running, need to apply throttle and it cranks to life like it starts on 2 cyl or so.
it runs great except that and starts cold and warm.
what to check?
it runs great except that and starts cold and warm.
what to check?
mbarryracing
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Do you possibly have an injector that is leaking down and flooding an intake port while it's sitting?
Jona$
Master
how can i test that?
fuel presuure guage in the fuel line. It should go down slowly but hold pressure for awhile. I told you awhile to put one in your fuel feed line. Sounds like fuel pump losing prime.
mbarryracing
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Could be fuel pump too, good point.
One way to see if the fuel pump is the issue if you aren't going to install a fuel pressure gauge is to cycle the key a few times before cranking, putting the pump in the prime cycle to build pressure. Then see if it will start on all cylinders.
If you smell raw fuel when it's trying to start on 2 cylinders as you describe, then the next thing to do is check for a leaking fuel injector that is flooding the motor while it's sitting.
A rather easy way to check for this, that sounds silly, and if your willing to remove the MCX intercooler plenum with the extra injectors is to stick paper shop towels in the plenum runners which will absorb any leaking fuel out of the nozzles of the injectors.
At the same time you should open the throttle plates on the engine and stick paper shop towels into them too to check for any leaking fuel from the stock injectors.
All towels should be dry after your time frame that it seems to flood. If any one is wet, there's your leaking down injector...
Just remember to remove ALL the towels before re-assembly, account for each one... LOL!
One way to see if the fuel pump is the issue if you aren't going to install a fuel pressure gauge is to cycle the key a few times before cranking, putting the pump in the prime cycle to build pressure. Then see if it will start on all cylinders.
If you smell raw fuel when it's trying to start on 2 cylinders as you describe, then the next thing to do is check for a leaking fuel injector that is flooding the motor while it's sitting.
A rather easy way to check for this, that sounds silly, and if your willing to remove the MCX intercooler plenum with the extra injectors is to stick paper shop towels in the plenum runners which will absorb any leaking fuel out of the nozzles of the injectors.
At the same time you should open the throttle plates on the engine and stick paper shop towels into them too to check for any leaking fuel from the stock injectors.
All towels should be dry after your time frame that it seems to flood. If any one is wet, there's your leaking down injector...
Just remember to remove ALL the towels before re-assembly, account for each one... LOL!
I have a buddies mcx does same thing. Thats what does also. Cycles the key a few times. He just needs new relay or pump. He's lazy.
Jona$
Master
well i have a fuel pressure gauge and it holds the pressure for several minutes.
gonna make the test with towels, but that should be anough with taking it apart, put some paper in its place and cycle the pump a few times with the ignition and wait for like a 15min and check?
right?
gonna make the test with towels, but that should be anough with taking it apart, put some paper in its place and cycle the pump a few times with the ignition and wait for like a 15min and check?
right?
mbarryracing
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The fuel system needs to be pressurized for both the stock injectors and the MCX supplimental injectors in the plenum.
Jona$
Master
that i understand and the all eight of them should be pressurized just by turning on the ignition.
Had 2 stops today with short time one at 10min and one at almost 20 and it got worse the longer the time. quite sure its a injector leaking. it sure seams like it.
So if im understanding it correct.
1. of with the intercooler
2.paper to the external mcx injectors
3.full throttle and put paper in carburators ?
4.cycle the pump a few times by turning the key
5.wait like a 20min and check all injectors for leak
correct?
Had 2 stops today with short time one at 10min and one at almost 20 and it got worse the longer the time. quite sure its a injector leaking. it sure seams like it.
So if im understanding it correct.
1. of with the intercooler
2.paper to the external mcx injectors
3.full throttle and put paper in carburators ?
4.cycle the pump a few times by turning the key
5.wait like a 20min and check all injectors for leak
correct?
mbarryracing
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Yes, unless it only does this when it's warn after it's been running. Then you'll want to make sure you run it first...
Jona$
Master
never tried just cyling cold and se if its hard to start. but a quick run and in to the garage and do the test should do it.
Jona$
Master
So took the chance now when doing some modding and did as said above and couldnt find any leaks at the paper, but a strong smell of gas in cyl 1 & 4.
Maybee a gascloud forms in one or 2 cyl because of leaking injectors and the reason it starts when applying throttle is because it gets more air and can start to ignate and start burning the fuel?
The next thing to trie tomorrow is cycle the pump and wait atleast 15min and open the throttles and smell if there is reacher anywhere?
Second is get it really hot and shut it of and do the papertrick?
because intill now i havent seen any leaks.
Maybee a gascloud forms in one or 2 cyl because of leaking injectors and the reason it starts when applying throttle is because it gets more air and can start to ignate and start burning the fuel?
The next thing to trie tomorrow is cycle the pump and wait atleast 15min and open the throttles and smell if there is reacher anywhere?
Second is get it really hot and shut it of and do the papertrick?
because intill now i havent seen any leaks.
APEX XPRESS
Extreme
The easy way to check the MCX injectors for leakage in the the plenum is to pinch fuel supply fuel line to injectors off.
Start engine up and let warm up (Do not boost engine)
Let set overnight and then see if it starts good now.
If it starts good now you have a leaking injector.
If this is the results next step is to pull cooler and do your paper trick.
Start engine up and let warm up (Do not boost engine)
Let set overnight and then see if it starts good now.
If it starts good now you have a leaking injector.
If this is the results next step is to pull cooler and do your paper trick.
Jona$
Master
As said, had the intercooler of for changing oil and some other stuff and did the papertrick with both the mcx and stock injectors.
Couldnt feel any wet parts, just a a weak smell off the paper from cyl 1 and 4.
The Mcx injector paper were totally free.
had it going to like 90deg celsius today when changing coolant, shut it off and went to start it like 15min later and it fired up but ran rough like 2 cyl and shut off, waited like 15 again and fired right up.
and that was with the intercooler of but the gasline connected.
any one out that there that can help me through this one.
Can i take them of and clean them or something?
Couldnt feel any wet parts, just a a weak smell off the paper from cyl 1 and 4.
The Mcx injector paper were totally free.
had it going to like 90deg celsius today when changing coolant, shut it off and went to start it like 15min later and it fired up but ran rough like 2 cyl and shut off, waited like 15 again and fired right up.
and that was with the intercooler of but the gasline connected.
any one out that there that can help me through this one.
Can i take them of and clean them or something?
Jona$
Master
So got my orginal injectors back today "tested in bench for leaking and pressure" and they were like new, no leaking or diffuse spray.
Wtf can it be then. i remembered the sled gave the same symptoms with mcx intercooler of so cant be it.
Note: did also a revalve after this and discovered that i needed to change 15 of the schims and now it is perfect, can that be?
Also sparkplugs? what more can i go on with this symptoms?
Wtf can it be then. i remembered the sled gave the same symptoms with mcx intercooler of so cant be it.
Note: did also a revalve after this and discovered that i needed to change 15 of the schims and now it is perfect, can that be?
Also sparkplugs? what more can i go on with this symptoms?
