Hey everybody, just started workin my new buy, a 1989 740 gl...w/a bosch injection system, the pump is new, FP relay, I got juice at #1 and #11 fuses, no juice at the injectors though, I probed and started and nothing, I'm used to my 90' 740 glt w/ Regina igntion. this thing only has 127,000, one of the reasons why I bought it....wondering whats between the injectors n the FP relay that could be keepin this thing from startin...any input is appreciated...

 

If I'm not mistaken, on /near your overflow coolant reservoir, there should be two identical relays. One is called the radio suppression relay. It actually controls the injectors. I don't remember which is which, but the relays are identical. I remember swapping them around to check and make certain the relay for the injectors worked. A manual would tell you which is which.

 

The relay on the water tank was different then the fuel pump relay in the fuse block. I replaced mine when I went through the FI system on my 89 740GL. I would suspect it will solve your problem. Mine died at 305,000 miles and I replaced all of the fueling components.

 

the radio suppresion relay is new but its not the one that comes for this car, sum idiot switched it out thinkin thats what was wrong with the car, it still has the 4 wires, gonna check that out, I have 2 new ones n I can always check them with the voltimeter n match conductuity, this car had problems before that, I bought this as is knowing that all these backyard mechanics dont know what the hell thier doin, too busy with toyotas, lol...anyhow, it has a new intank FP, relays are new, all fuses, got a spark to the engine so I know it has nothing to do with that, got a PDF on this car too so I'm prepared, you helped me out alot with my 91' 740, I still cant believe how crappy runnin that car was when I bought it,I love my car now, thanx...p.s. my girl loves ur car...lol.. u have a youtube channel?

 

checked the voltage on the RS Relay, it has 12 volts goin into it through the red wire(the diagram states that its brown) like 10 volts runnin out(blu/yel) to my idle control valve, and . 52 volts going (grn/red) to my injectors, is that too small of a current to activate the injectors? gonna start switchin to the original Relay to see what happens...okay, didnt switch it, but I can hear it click when I go to turn the car on...so it does work, but is it giving me the proper voltage goin to my injectors? dont know how much is supposed to be comin out of it towards my injectors...?

 

Doesn't sound like enough voltage but I'm not good with electronics.

I was going through some issues myfelf. Maybe its your Hall sensor inside the distributor.

No Start on 740/940

 

Got like 2 of those that came with this car, more of the many things that were replaced by whoever tried to diagnos it, definitly gonna check that, do u know how much output the hall sensor is supposed to have? anyone? on my pdf, I only see a impulse sensor, I have an 89' Bosch ignition, 2 pumps, dont know for sure if its the 2.2 jetronic.....gotta check that out....

 

Are you getting any codes out of the OBD. If so what are they. My 89 was starting to have starting problems so with 310K miles on it I decided to go through the FI system. I replaced the in tank and main fuel pumps and filter. I put a new fuel pump and radio suppression relay in. I then replaced the crank sensor. I have always replaced the timing belt and tensioner along with the dizzy cap , rotor and wires and plugs at 50,000miles. I touched the key and in about 3-4 seconds it starts right up. It does it every time. It's my wife's car and she her next goal is 500K.

 

I dont have an OBD, I check every curcuit with my volitmeter, wish I did though, the intank pump is new, relays, dizzy cap, havent check the cran sensor yet, tomorrow I'll check the hall sensor and acouple of other things, gonna reset the timin as well, I dont know who tried to diagnose this car but by what the old man that I bought it off told me atleast 4 people have messed with it, each one with thier own theory, I have a 91' 740 that I brought to life little by little, so I've learned alot about these systems, the 89' Bosch is not that much different from my 91' Regina..only the ignition and the pump situation only having one...I'll start early tomorrow...see you ack here and thanx for the input...

 

You have the volvo version of an OBD. It is located near the driver side shock tower inside the engine compartment. It is a small rectangular block with a led in it. Check here for instructions Troublcodes.net Trouble Codes OBD & OBD2 Trouble Codes and Technical info & Tool Store. By BAT Auto Technical

 

Well, there could be some confusion here on OBD. N/A cars got LH2.4 and OBD in 89. Turbo cars stayed LH2.2 in 89, didn't switch to LH2.4 until 90 so.......is it turbo?

 

not sure if you fixed this but...
On the fuel suppression relay point, with the ignition off test plugs with ohm meter as follows
terminal 1 to gnd 0 ohms y -ok n- check wire for open
terminal 3 and terminal 1 of any injector 0 ohms - ok , n- check wire for open
disconnect all injectors and check terminal 3 terminal 1 of any injector reading infinity - ok , n - check for grounding of lead 3 wiring

last check with ignition on terminal 1 and 2 should read 12v - ok , n check for open on terminal 2 and contact 87/1 on system relay

also if you can check detail wire diagram since there are connector points in the wiring in questions

 

that is cooooool. thanx for the info on that OBD....didnt even know that...i love these cars...

 

Another good set of LH2.4 OBD howto info.....

Engine and OBD Diagnostic Codes

with that little box, you can read two different sets of error codes, socket 2 for fuel injection, and socket 6 for ignition related stuff. only some codes light the check engine light, basically the ones that relate to smog systems. you can also put the computer into 2 different diagnostic modes where it repeatedly cycles various actuators and relays so you can test the, and other set of test modes for testing the various sensor inputs.

 

Hey everybody, I switched my crankcase pos. sensor, n pulled the codes, its 1 1 1 which means theres nothing wrong, could it be the hall sensor not igniting the fuel injectors? I have 2 extra ones so I'll switch those...be back after that....

 

and theres no hall sensor in the dizzy cap ignition chamber, niether does my 91' 740 Regina...?

 

The LH2.4 and Regina cars use a reluctor sensor on the flywheel bell housing. That's really dependent on the ignition system, which should be Rex 1 for Regina cars and EZK116 for Bosch LH2.4.

 

the LH 2.4's OBD has a Test Mode 3 where it cycles all the actuators on the fuel side, this includes the injectors. with a test light, it shoudl be pretty easy to follow the pulses from the ECU to the 'radio suppression' relay to the injectors.

see "4. Diagnostic Test Mode 3: Injection System Component Activation Test" on that OBD link I gave above.

 

no turbo..

 

I switched the crank case sensor from my 91'(my main car) to 89', the 91' turned on fine, the 89' didnt, checked for a spark, got that, took off the cap n put the engine @ TDC, then noted that the rotor was looking down, I took the cap off my 91' to reference check also TDCing it and noticed that the timing was off by 180 degrees on the 89', fixed that, then went to crank and got nothing... didnt get to run the OBD, its dark out now... but im jumpin on this as soon as I wake up, the ex owner came by and told me that he even got the cpu changed, which one, dont know yet...it seemed that sumone had told him when a first the car started giving him problems that it was the timing, n they screwed it up, and everybody that dealt with the car after that gave him the "it could be this? theory" and he replaced everything tryin to get the car started, well he also told me the car has been sittin for almost 5 years...its still not gettin juice to the injectors...voltage tested that before I wrapped up just in case...niether is the cold start valve, he said it would start if you shot sum starter fluid in the throttle.. but would of course then shut off... gonna do the rest of the OBD tests tomorrow... hopefully I'll figure this out... you guys are the best...I know together we can get this thing started so I could move on to the next project....