Jump to content

3.5 efi no start - electrical gremlins?


joe1
 Share

Recommended Posts

This is a 87 rangie. Bought a non-starter (it didnt even attempt to fire, just turns over) I've been through various ignition/fuel checks and replaced the following: dizzy amp (pickup coil was fine), cap and rotor arm, and ignition coil - now get sparking at plug lead. Also re-set timing which was well off - whipped off the rocker cover to be sure valves were rocking. However, still no-start.

I'd checked fuel pressure first off and found around 40psi, so assumed everything there was ok. However I've noticed some intresting things - which may or may not give clues as to what's going on. The only warning light showing with ign on is the charge light. No low oil pressure light nor anything else (although earlier I may have seen the oil pressure light briefly - can't be sure). And the revs on cranking don't show either - although they definitely did earlier in the week. And recently I can't say I've heard the fuel pump either (although I definitely did hear it when I measured the pressure). Is the lack of tach signal or warning lights useful pointers to the non-start issue, or completely irrelevant? I've got the early efi manual so am about to do some checking of signals at the ecu end of things, but I've got the feeling its all going to take some time...... Cheers for any insights you might be able to provide, Joe

 

Link to comment
Share on other sites

I saw yesterday that the main and fuel pump relays had been changed for new ones - the old ones were still in the car. So put the old ones back in and hey presto, I now get oil pressure light and the revs show when cranking. Fuel pump runs as well, and occassionally the 'Brake' warning light is on as well. All the tests I then did with the cpu pass spot on, so still clueless about the no-start. Plugs are wet, so it has to be ignition-related, Next step to change plugs and leads for new,and perhaps change the dizzy amp for a remote one that might give more oomph......

Link to comment
Share on other sites

I find they need to be spinning fast to start, make sure your battery, starter and cables are working well.

Have you tried compression, they have to be quite bad not to run but I've had it and as you've never run the engine you don't know how bad it was before it was parked up.

I would check the timing manually, ie turn the engine by hand until the inlet valve rocker on cylinder 1 has opened and closed and piston 1 has come to the top (use something pointy through the spark plug hole to gauge this). Then check the rotor arm is pointing to the plug lead going to number 1. Then check the leads are correct from there following the firing order. If the movement of the cylinder and the valves doesn't follow that sequence then check the chain, cam, pushrods etc and retime the engine.

From memory the fuel pressure in the rail should be 2.5bar above inlet manifold pressure which I guess would be somewhere near your 40psi.

If I remember rightly there is an over run relay that turns the injectors off when the flap valve is closed, mounted near the flapper valve. Not sure if this is ignored during cranking, my memory is hazy, but worth checking. I took the whole fuel rail off mine with the injectors and put a plastic cup under each one to see if they were all spraying nicely, it gave an idea if they were all kicking out the same amount of fuel after a few cranks of the engine. Maybe not quite safety approved as the engine will still be sparking but I lived ;) .

The ignition module on the side of the dizzy has given me trouble before and caused none running.

Don't forget to look for air leaks, if someones been trying to fix it maybe they've left something out or not sealed something?

Failing all of those there is a really good fault finding manual in the tech section of this forum, I used it a few times, go through it starting at test 1 and see what comes up. It covers the ECU as well.

Good luck :)

Link to comment
Share on other sites

My 2c from playing with mine before I ripped it out for a MSII, mine was so rich it would only just start and run. First I disconnected the cold start injector, it isnt really needed, I found mine had an extra resistor soldered between the temp sensor and gnd to alter the fuel (leaner I think), taking that out didnt seem to do much. The temperature sensors can fail and make them go rich. They can loose prime on the oil pump as well so check the oil pressure

Link to comment
Share on other sites

Good points:

@Cynic-al: yes I kick myself for not doing more sequence checking when the rocker cover was off - all I was sure of was that no 1 valves were rocking (exhaust on no.1 had just closed and inlet was just about to open) so that had to be TDC - and then the cover went back on. I should also have done all the compressions earlier as well. However, if all the compressions do check out (tomorow's job), then I can hopefully assume that all the valve gear is working ok - ie, no broken cam, and no bent pushrods. And yes the ign lead numbering/sequence is right. So that should sort the basic checks.

And today, the no revs on crank and oil light dissapeared again - so there must be a common fault/connection that is going out, have to check some more - obviously putting back the old relays was just a coincidence. But I'll say one thing that bothered me a bit was when I originally checked the engine using my thumb over cylinder 1 spark hole, was that the rotor arm was pointing to the cap segment for cylinder 4. Not sure with a v8 but isn't that 180degrees out - so had someone fiddled and got it wrong, or was the engine somehow originally timed 180 out - makes my brain hurt thinking about that, but anyway can't really see how it could run like that.

I'll check for overrun relay, not sure at mo, I've done the basic checks listed in a TVR wedge document I found (not found the one here yet), and they all checked out - but getting ahead of myself, need to change the plugs (thanks FridgeFreezer) first really. And no kidding the spark at the plugs isn't great - one reason I wanted to change to a different amp.

@Cheesy, yes, will check sensors later on, already disconnected the cold start just in case there was something there.

So, next I'll complete the basics, and see what happens, will report back. Cheers for the helpful pointers.

Link to comment
Share on other sites

One of the downloadable manuals has a good trouble shooting section to go through, it makes it a lot easier. I got mine going then fixed some rust after which it wouldnt go again, turned out a bit of metal from the grinder got into the fuel pump relay so the contacts wouldnt close properly, it did still click though! took a while to figure that one out

Link to comment
Share on other sites

The rotor wants to be pointing at plug lead 1 after the inlet valve has opened and closed on cyl 1 and the piston is at the top. That should be good enough to get it running, after that you can tweak it with a timing light. If you don't want to take the rocker cover off again I think you can see one of the rockers through the oil filler hole <_<

The manuals I refer to are here;

The test procedure has saved me no end of agro in the past!

  • Like 1
Link to comment
Share on other sites

+Cynic-al (and mods): There's a broken link to the pdf files in the link you gave - and a search for 'diagnostic manual' in the tech archive doesn't reveal anything - "The page you requested does not exist...... Thanks though 

Link to comment
Share on other sites

Join the conversation

You can post now and register later. If you have an account, sign in now to post with your account.
Note: Your post will require moderator approval before it will be visible.

Guest
Reply to this topic...

×   Pasted as rich text.   Paste as plain text instead

  Only 75 emoji are allowed.

×   Your link has been automatically embedded.   Display as a link instead

×   Your previous content has been restored.   Clear editor

×   You cannot paste images directly. Upload or insert images from URL.

 Share

×
×
  • Create New...

Important Information

We use cookies to ensure you get the best experience. By using our website you agree to our Cookie Policy