1999 Isuzu Rodeo, 4 cylinder. Intermittent Start...If I switch ON (dash lights up)2 or 3 times, but don't crank... It will definitely Start on next try. Runs fine.. battery, Alt New. Do you think it's the fuel pump or electrical in switch?

does car have and immobilizer on it (we dont this car in usa)thanks of saying country... VG!
intermittent no cranks!
check battery lugs for the green corrosion.?
to diagnose, no cranks, like this takes using a voltmeter. (at point of failure)
to find out witch path fails.
loss of battery power,(batteries are notorious for this) 12.6vdc rested ,
next time it don't crank, jumper cable crank it over, off a donor car.(like tow trucks do)
or swap in a known good battery form other car.
does it crank now? if yes, suspect a bad battery.

no? then we hot wire the starter solenoid,
no crank now? then bad starter.(intermittent)
or if it cranks now, yes, then a bad key line/
i'd scan the PCM to see if it's the immobilizer, blockage,(bad key errors,etc)
or other issues.
my guess it's an automatic transmission
crank it , in neutral? the operators guide shows how to do that.
if it always starts in neutral, then the Park switch is bad, in trans.(intermittent as all do)
eventually.
or intermittent starter relay.
(diy magic)
rap the relay with end of screw driver, crank now?
wiggle shifter, in park start now?>
crank in neutral, start now?
rap side of starter, with dead blow hammer, gently
like cracking a walnut not breaking rocks.
did those allow cranking?
wiggle those 2 huge battery cables. crank now>?
end magic.

first post is a viable option but i would do some diagnostic work first , check the OBDII codes as may be a sensor/switch that has overheated or got fried , check cylinder compressions to check for head gasket etc

gas engine? sure.
no crank security system.
my guess is you mean the car has and Immobilizer option on car?
most cut fuel.
all have a light, if the lamp is not there, you dont have it.
key on, the cluster lamps tell you if it has IMMOBLIZER ACTIVE.
meaning .
so if the lamp is not there, or is not flashing or glowing cranking
then that is not the ISSUE !
sure we look first...
then we.......
1: check for spark. got spark to all cylinders
yes, if not scan the pCM cranking, it will tell you what spark is gone, 90%
2: yes spark is good, now i check spark timing with 20 buck light.
its way off, the cam belt slipped, FACT.
yes timing is ok.
3: all engine , not blown up overheated , all perfect for 3seconds on test fuel (you do that with spray) does it? if not sounds bad, it is.
if it goes, verrrooooomm stall, its GOOD>
repeat over and over, until happy, see engine and spark is good.
4: ok test fuel tests PASS muster.....
so that leaves what, fueling.
a: too much is called flooding, use WOT cranking to clear floods.
wot means wide open throttle or as ,truckers call it pedal to dah metal..
this cuts all fueling to clear flooding on all EFI engines.

b: no fueling, the spark tips are dry.?
check pump pressure after scanning PCM.

the ECU cuts fuel for 3 reasons. (pure logic)
a: Tps stuck WOT.
b: lost spark (ignitor or tacho dead)
c: lost CMP or CkP sensors (cam, or crank)
the ECU reports a and b, and not c. as c is a FEATURE not an error.

it sounds like u have something stuck in the engine ,u should be able to turn the shaft manually.so tear it back down and look for something in there or something stuck.dont try to force the engine to turn it over.if it just wont start and does turn over ,set the timing by putting the cylinder on #1 and make sure your timing marks line up.

1-3-4-2

what was the code number?

Where Is The Camshaft Position Sensor Located On A 1999 Isuzu Rodeo?

If P1627 is set when there is a problem with the fuel level sending unit, 100% sure on this problem, replace the fuel level sender in the gas tank, about 2.5 hours, very straight forward job

check battery cables & terminals for tightness & corrosion.also check at starter.check starter bolts & actual starter for looseness.if no problems found your starter may be on its way out.next time it happens hit starter with hammer or heavy object if it starts right up get ready to replace it.good luck