3rd Gen - WONT START!

bethany_mayx · Post by **bethany_mayx** » Sat Feb 02, 2019 4:56 pm

Hi everyone, sorry it’s going to be a long post but I am absolutely stumped on what to do now.

Basically, my 1990 2.0 twin carb prelude ran with a misfire for a couple weeks, I found split rubber mountings on the carb/intake manifold so I know that’s an issue.
I came back to the car after around 3 weeks and tried to start it, it cranks over but doesn’t actually fire up.
Inititally i checked all the spark plugs which were new anyway, they all weren’t good condition and had good gaps. Next, I changed the HT leads (not the king lead) and still nothing.
I then took off and checked the air intake and the filter was clean and no blockages.
Next, I took the fuel line off just before the carbs to check the fuel pump and it was fine, I was getting fuel pressure.
I then assumed it must be my carbs that are blocked up so I took the carbs off and sprayed ‘easy start’ directly into the intake whilst cranking and it coughed once at me but that was it. Still didn’t fire up.
I went back to back and got a spark tester, I discovered the spark was really weak. I checked the battery which was fine. I then replaced the earth cable from the rocket cover to possibly improve the spark? Still cranking but not firing up.
I took the dizzy cap off which was brand new and all 4 points had a good amount of wear on them so I knew the rotor was actually touching them. The rotor arm is also new.
I then ordered a new ignition coil from America which also did nothing.
I took apart the dash and checked the ignition (main relay) and resoldered the points. The fuse is also fine and all the wires leading towards the coil are in okay condition.
I took the whole distributor off earlier and checked the connection between the blue and ground and yellow/black to ground and they both came back as near enough 12V.
I’m completely stuck on what I need to do now.
Do I need a new distributor or do I need a new main relay?? Any help is appreciated thank you!

Post by **Drax** » Sat Feb 02, 2019 8:16 pm

@Wurlycorner

firstlude · Post by **firstlude** » Sat Feb 02, 2019 9:05 pm

Just a thought have you checked to see what voltage your getting at the coil when your cranking

bethany_mayx · Post by **bethany_mayx** » Sat Feb 02, 2019 9:16 pm

firstlude wrote: ↑
Sat Feb 02, 2019 9:05 pm
Just a thought have you checked to see what voltage your getting at the coil when your cranking

I checked the voltage of the old coil and it was 8V (not cranking) just with the ignition on. Not checked the voltage of the new one

89 UKDM BA4 4WS (resto job!) · Post by **wurlycorner** » Tue Feb 05, 2019 1:17 pm

Hi there bethany
Welcome and sorry to hear of your lude being grumpy at you!

Great load of detail there on what you have tried etc. and all looks like a sensible/logical approach to me.

I'm not intimately familiar with the carb 3g setup so have just had a look at the OEM service manual and my first reaction was...

Holy crap, could they possibly have built a more complex setup?!

(no, seriously...

it's proper mind-blowingly complicated - they have basically built the most complex EFI system ever and the bolted it around a carb

). This is a carb system, with a MAP/O2 Sensor/EGR/IAT/Vaccum/Speed Sensor/Electric Fuel Pump/EVAP etc. but still using an auto choke, not to mention the most complex ever in the history of anything, vacuum system going to all kinds of valves. It's nothing short of nuts!
I challenge anyone to look at the vacuum diagram on page 6-7 and the basic system flow-chart on page 6-13 and not think... WTF?

Anyway...

I think the first thing to check is... Have you yourself got a copy of the oem service manual?
If not, you can download from the forum, here;
kb/viewarticle?a=10

I suggest starting to see if there are any fault codes logged in the ECU. Page 6-90 of the manual tells you how to read these.
Probably nothing is logged (it's a VERY basic self diagnostic system on this car) but it's worth a shot.

If not, then the manual contains fault finding guides (Page 6-20 on) which should prove helpful - although they can take ages to work through and you might commonly find yourself ending up part changing too soon (e.g. 'substitute known good ECU') when actually what you should do before deciding that, is move onto testing the other possible systems first.
However, if you follow them through, they can be very helpful in ruling out what AREN'T problems, in a methodical way.

Don't forget to refer to the Electrical section of the manual as well, because this is where the wiring diagrams are and it explains more detail about the ignition system etc - not covered in the Fuel and Emissions section.

Just going on the basis of what you have tried and reported back on, to me it *sounds* more like an igntion fault, rather than fuel.
I say this because you have confirmed fuel pressure and have tried easy start (which should basically over-ride any fault in the fuel system).
That said, if you've confirmed you have spark on all four spark plugs, it's probably worth checking the timing, before going any further.

Whereabout are you in the country?

89 UKDM BA4 4WS (resto job!) · Post by **wurlycorner** » Tue Feb 05, 2019 1:17 pm

meant to @bethany_mayx for the post above.

Interested to follow this one through.

Also note there is also a Haynes and Chilton manual that cover the 3g.
They can be helpful because they include pics etc but obviously don't contain anything like the level of information that is in the original Honda service manual.

sol-lude · Post by **sol-lude** » Tue Feb 05, 2019 4:45 pm

Holy complicated vacuum diagram batman. That is positively mental at least the break it down in the following pages. Will be interesting to see the outcome.