Can't cold start. No pulse at injectors

(Alexandre G Fortin) #1

My XJ40 1988 can’t cold start without ether in the intake. After it runs for about 5-10 min, it re-start well. The idle is a little low (around 700-800) but everything seems to work fine, exept a speaker…

There is not pulsating in the injectors at ignition. What could cause that, and how come it re-start after running a few minutes? (Im a bit of a newb) When its humid/raining, the car doesnt restart after a 1h drive. It needs ether for any start.

Fuel pump works well, pressure in good. Crank shaft sensor, and well as temperature sensor changed. I tried another ECU, same problem. Alternator was rebuilt lately, battery is new. Theres 12v at the injector but no pulse. I cleaned a few grounds… what else… all relays work fine. Theres is spark.

Any ideas?

Error in dashboard : fuelling failure 1 and 6, they alternate…

It is not the fuel pump, pressure in/out was tested.

(motorcarman) #2


Fuel Fail 6- Air mass meter failure (high throttle potentiometer Voltage with low air mass meter Voltage).

Could be your TPS is faulty or adjusted incorrectly??
MAFS faulty??

XJ40VCM.pdf (690.7 KB)


(Robin O'Connor) #3

Isn’t this the third thread started for this problem?

(Alexandre G Fortin) #4

Yes. No one seems to have any idea…

(Bryan N) #5

Not true. People have responded with a number of ideas - apparently not the correct ones - but starting a new thread after each failed attempt isn’t going to help much

(Mike Stone) #6

Bryan, I wouldn’t say starting a new thread won’t help much - I would say it hurts! Someone seeing the new thread without having seen previous posts (threads) about the problem may well suggest fixes that were previously suggested. Plus, anyone researching the same problem in the future won’t get the full history unless they chase down the multiple posts.

(Robin O'Connor) #7

Agree, unless Axleandre can rule out the possible fixes that have been suggested I for one am giving up on this thread(s)

(Alexandre G Fortin) #8

Sorry about that, first time posting on the forum. My problem still has not been fixed yet, even your suggestions…

I hae seriously no idea abot what to do, exept start it with ether in the morning. Sometime it also start without ether, when the weather is dryer.

Fuel pressure is fine according to a mecanician friend (40-48 in, 20 ish out).

I also note that it starts better qhen the radio is closed for some reason.

Sorry for the other treads.


(Alexandre G Fortin) #9

Crankshaft sensor has been chaged to a new one, i also change temperature sensor and mass air flow sensor : nothing changed.

(Robin O'Connor) #11

Is the air filter clean?

(Alexandre G Fortin) #12

Air filter is clean.

It drinks 91 usually, and 94 where i can find it… (mostly in the country side where theres boat (im in canada), since it doesnt seem to have more then 91 in the city.

(Grooveman) #13

Fellow enthusiasts …

All this talk of Octane Levels !

I humbly suggest you go online and educate yourself on what exactly octane levels mean. Octane is added to gasoline for one reason only , to prevent engine preignition of the air/fuel mixture in the combustion chamber, better know as “engine ping”. Higher octane gasoline DOES NOT increase performance, increase torque, clean better, or give extra gas mileage.

Gordon, 95-98 octane fuel ?? WHY ?

(Grooveman) #15

Gordon …

OK I’m never too old to learn. “More power, more miles per gallon” … could you please direct me to any of the sites on the internet that might document your statements.

(Grooveman) #17

Gordon …

True … A larger (greater energy released) explosion in a combustion chamber will, all things being equal, produce more power in an engine.

False … More octane produces a larger explosion. Once again octane does not produce more power! It ONLY delays pre-ignition of the fuel/air mixture. If your ignition cycle is properly timed and no pinging is occurring more octane will NOT produce more power.

So why do you have to use higher octane fuel in some newer engines or engines in super cars … because they achieve their performance with much higher (and sometimes crazy high) engine compression ratios.

Gordon I love learning new things :grin: so once again please direct me to your documentation. And please don’t think I’m trying to “call you out”. All the research I’ve done points to this being a very well established urban myth but maybe ???

(Robert King) #18

Saratoga Air Group VF-3 used you logo during WWII

( Larry ) #20

Add a pint of kerosene to your gallon of 91 and you’ll make maybe 92/93 or so :open_mouth: - high octane gas, (as groove says) is LESS volatile so it doesn’t pre-ignite on high compression.

High-test beer is a different kettle of fish though.

(Robin O'Connor) #22

Possibly because the engine is designed to run on the higher octane???

(Grooveman) #23

Robert …

“Felix the Cat” has a rich history in Naval aviation.

I was a pilot in Fighter Squadron 31 (VF-31) “Tomcatters” flying first the F-4 Phantom and later transitioning to the F-14 Tomcat flying off the USS Saratoga and USS JF Kennedy. VF-31 is the second oldest Navy Fighter squadron behind the VF-14 “Tophatters”.

You can just imagine our joy as the long time Felix Tomcatters actually started flying the F-14 TOMCAT !!

Check 6 baby

(Gordon) #24

So what is the recommended fuel for a 1991 Daimler 4.0. manufacturer ?

(Robin O'Connor) #25

I ran my ‘92 XJ40,(essentialy the same engine) on 91 octane quite well for about 9 years with no ill effects and occasionally used 95 with no discernible difference. This is in NZ be aware that the US use a different rating for their octane(s)