intermittent no start

eddielee · Post by **eddielee** » 19 Jan 2016, 09:45

Hello,
I am new to this site and have a question about where to start next.

My Ex has a 1993 850 GLT and it is having issues.

First off I noticed that the air filter hose had holes and needs to be replaced. I taped it so that there is no air bypassing the MAF and the MAF code went away. Will replace when possible.

There is a list of codes which I cannot remember, however, the codes I think need addressing are the Cam sensor missing and cam sensor sporadic. The other is the Engine speed sensor sporadic. The other codes were from other ports like the trans drop solenoid faulty and not seeming to be tied to the engine running.

I work on my truck which is a Dodge ram 2500 Turbo diesel. With the Dodge a cam sensor or a crank sensor can stop it from starting.
An old Toyota of mine would compare the two and not start if they did not match, or throw a code for both if one had an error.

So my question on the sensors, after reading what could be found, should I replace the cam sensor first and see if the crank code goes away, or should it be the other way around. I have learned to only do one thing at a time as one part affects another on most vehicles. Should they really be done together?

Is there a good site to get parts from which sells OEM parts at a discounted price? I read that like many other makes of cars these Volvo's only like OEM.

eddielee · Post by **eddielee** » 19 Jan 2016, 11:47

After more searching it appears that the Cam sensor is the one to start with.

Will a faulty cam sensor cause the intermittent crank sensor code?

Post by **scot850** » 19 Jan 2016, 19:25

I had an issue with a cam sensor on a 93 850 NA (GLT). The sensor was marginal to it's resistance, but what had happened was the car had been worked on and I had moved the cam sensor wire so it ran too close to the distributor. The distributor signal would mask the cam sensor randomly and either prevent the car starting or the engine would stumble or cut out and then re-start.

I didn't find any codes, so I took to the dealer and they said the problem was the cam sensor, and they wanted 1.5 hours to swap it out. The mechanic was pissed as I refused the repair, bought a new sensor and fitted it in about 10 minutes. I had noticed the wire was running close to the distributor and someone on MVS suggested this may be the problem, so I re-routed the cable as far away as I could from the distributor and no further issues. I checked the old sensor and was tempted to put it back in, but as the original was marginal, and 17 years old I kept it as a spare and left the new one in.

Sorry, but can't remember the measurement value for the resistance on the cam sensor.

Neil.

eddielee · Post by **eddielee** » 21 Jan 2016, 13:45

Thanks for the input.
I looked at the wires and all are in their stock positions.
Ordered new cam and crank sensors beings there's codes for both of them, and she said it started then died this morning.
Will post results when done with that.

She said it didn't like going over 40mph either. Any thoughts on that?

Post by **scot850** » 21 Jan 2016, 22:59

It is probably connected, if one or both sensors is actually faulty, then the engine can't read the signals it needs to give power.

Replace the sensors first and then post back.

Neil.

eddielee · Post by **eddielee** » 26 Jan 2016, 08:02

So for the update,
I went ahead and replaced both sensors, no start still.
The fuel pump is not running now so gotta replace that too.
Last time I was looking at it the pump was running, checked for voltage with DVOM and it was 11.5ish and pump did nothing...
GRRR, I wish she had never bought this car! Wouldn't care if she knew how to work on it...

Post by **erikv11** » 26 Jan 2016, 08:10

Your best bet on the fuel pump is Bosch 69693, that is the OEM part but far cheaper than buying it branded that way.

I would also swap the fuel pump relay, it is a common source of intermittent no-starts. A junkyard relay is a good place to start, for troubleshooting purposes. My first thought was that your pump is fine just change the relay, but I see you have voltage at the pump. Remember the pump only runs for a few seconds after you turn the key to position II, then the relay shuts it off.

eddielee · Post by **eddielee** » 26 Jan 2016, 08:37

erikv11 wrote:Your best bet on the fuel pump is Bosch 69693, that is the OEM part but far cheaper than buying it branded that way.

I would also swap the fuel pump relay, it is a common source of intermittent no-starts. A junkyard relay is a good place to start, for troubleshooting purposes. My first thought was that your pump is fine just change the relay, but I see you have voltage at the pump. Remember the pump only runs for a few seconds after you turn the key to position II, then the relay shuts it off.

That is why I had a friend turn the ignition on while I checked voltage.
I had opened the relay and watched while it opened with the key on, and the pump was running initially.
When I looked at it previously the pump was running and no start, last time not so much...

eddielee · Post by **eddielee** » 26 Jan 2016, 08:44

The pump you mentioned is stock for the 93 model? Or is there a plug modification I will have to do?

Post by **erikv11** » 26 Jan 2016, 09:27

Hmmmm I do not know much at all about the specifics of the 93 models, all I can note is that the parts houses all list all the same pump for all p80 cars, 93-00. It should be fine, here are a couple threads pointed to recently for doing the fuel pump routine:

https://www.matthewsvolvosite.com/forums ... hp?t=60613
http://volvoforums.com/forum/volvo-850- ... ump-71849/