1800: What does this damaged capacitor do??

[ChasesDragons]

Laird,
Basically, the car does start from cold, it does crank a few times beforehand, though. The pump is heard to run too.

On starting it seems to be missing cylinders and stalls within about 3 or 4 minutes with a heavy smell of raw fuel(fresh). Sparks are black and coated in raw fuel, no indication of bore wear (oily plugs).

Restart doesn't work a lot of the time unless a break is given. So, I don't know if this simply gives time for the flooding to evaporate.

I need to check fuel pressure at the rail and pump. The pump is noisy at low fuel level. The rail seems to have the adjustment screwed all the way in. - i don't know if this had been like this before the issues started. This setting doesn't seem rational as most systems in a car tend to be set in the middle range than limits.

Hope this helps.....?

Originally Posted by Laird Scooby

What exactly are the symptoms, does the engine being cold or hot make a difference, does it start doing whatever after it's been used a while or is it after a short drive, switch off and then restarted? Any other circumstances you can think of (relevant or not) would be helpful.

Just to clarify, it's the D-Jetronic injection and not twin carbs?

[Laird Scooby]

When you next try a cold start, try opening the throttle very slightly with your foot - about as much pressure as you'd need to bring a hot engine up to ~1500rpm. From your description, it sounds as if the the AAV (Auxiliary Air Valve) isn't opening to let additional air on for the cold running. It's a long time since i did anything with D-Jet but fairly certain they have one.

If opening the throttle a bit helps matters, it would be worth investigating the AAV if you have one, sometimes cleaning with Air Intake/Carb cleaner can bring about a recovery as they're usually stuck closed (hot position) and the bi-metallic strip that opens them has got a bit lazy and coupled with gummy residue tend to stick. If this is what you find, try squirting the inside of the AAV with carb cleaner when the engine is hot (valve closed) and a few more squirts as everything cools down.

[ChasesDragons]

I think my AAV was not working from the outset of ownership, in that it used to idleroughly, but smoothed out as it got warm. I will do the cleaning attempt regardless, thank you.

[ChasesDragons]

Just for my continued research should this also degenerate into a fuelpump hange:

https://www.brickboard.com/RWD/index...422&show_all=2

This talks out i stalling 2 port pumps in place of the 71 3 port one which is NLA

[Laird Scooby]

Originally Posted by ChasesDragons

Just for my continued research should this also degenerate into a fuelpump hange:

https://www.brickboard.com/RWD/index...422&show_all=2

This talks out i stalling 2 port pumps in place of the 71 3 port one which is NLA

To be honest, it sounds more like it's overfueling, hence my suggestion about opening the throttle a bit while starting from cold.

Also do you have PCV on that one? If so, when was it last serviced/cleaned out? That can make a surprising amount of difference to cold starting and general running too.

[142 Guy]

I would agree that black spark plugs and the smell of fuel are signs of over fueling and likely is not just an 'at start up' problem.

Checking the static fuel pressure is a good start; but, there are other things that can cause the engine to run with a low AFR. After setting the base fuel pressure to the correct value with the engine running, do a static fuel pressure test with the engine not running. If the fuel pressure drops like a rock then you have a leaking cold start injector, leaking main injectors or a leaky fuel pressure regulator. Prime the fuel system to re establish pressure and clamp off the fuel return line from the fuel pressure regulator. That will prevent loss of pressure through the regulator. If the pressure still drops like a rock you likely have a leaky cold start injector or main injectors and you need to pull them out of the manifold / holders to find which one is leaking.

Running with a low AFR can also be caused by failed / out of spec temperature sensors (both the air and coolant sensors) or wiring problems in the wiring to the sensors. The insulation on the wiring to the coolant sensor mounted in the front of the head is particularly prone to heat damage which results in the insulation crumbling and falling off.

If you are a vintage D jet owner, get the Volvo fuel injection fault tracing manual. It is your best friend when it comes to figuring out problems with your D jet system.

http://volvo1800pictures.com/documen...lt_tracing.pdf

[ChasesDragons]

I will put this here for future researchers;

I think this is the proper fuel system routing in the 1971 to 1973 P1800E which have the weird Fuel pump with the 3 ports.

The later ones have the simplified 2 port fuel pumps supported by 3 port Fuel Pressure regulators.

[142 Guy]

From capacitors to fuel pumps. I guess this qualifies as a threadjack.

I am not an 1800 guru; but, I believe that the 'weird' 3 port pump with all three hoses connected to the pump head was used on the 1970 and 1971 1800E. In 1971 Bosch introduced a revised 3 port pump with the discharge line moved from the pump head to the end of the motor housing so that the electric motor was immersed in and cooled by gasoline flow. I expect that this change was done to extend the life of the electric motor. The revised 3 port design was used on the 1971 140 E; but, not on the 1800E.

In 1972 Bosch revised the 'revised' 3 port pump by eliminating the external overpressure relief line (3rd port) back to the tank and I believe that both the 1800 and 140 received this 2 port design with the discharge line fitted at the bottom end of the motor housing. I have the noted Nissan 280 Z fuel pump which is pretty much a drop in replacement for the later 2 port pump and is an easy fit for the revised 1971 3 port version on the 140 after blocking off the return line to the gas tank. It will probably work as a replacement for the early P1800E 3 port fuel pump; but, will require some plumbing modifications because of the location of the discharge port.

[ChasesDragons]

Thank you for your description on doing to 3 port to 2 port conversion. All the capitals following are to highlight terns not to hout;

Do I understand the three ports on the pump form FUEL FROM TANK, FUEL TO INJECTORS, RETURN FROM INJECTORS?

When you say the 2 port conversion involves simply blocking the hose, do you mean the hose that is the RETURN FROM INJECTORS? Essentially changing the system into a "DEAD HEAD" system? Would this mean a different type of regulator used at beginning of the fuel rail and the rail is essentially into the dead end (head)?

Or am I misreading? is the return line from the injectors now being sent straight to the tank?

Two Qs arise if not; are the injectors going to get hot as the relatively stagnant fuel absorbs heat? Can it also increase vapour lock?

The more we talk, the larger this can of enquisitive worms seems to be! 👀🤣

[Laird Scooby]

Originally Posted by ChasesDragons

Thank you for your description on doing to 3 port to 2 port conversion. All the capitals following are to highlight terns not to hout;

Do I understand the three ports on the pump form FUEL FROM TANK, FUEL TO INJECTORS, RETURN FROM INJECTORS?

When you say the 2 port conversion involves simply blocking the hose, do you mean the hose that is the RETURN FROM INJECTORS? Essentially changing the system into a "DEAD HEAD" system? Would this mean a different type of regulator used at beginning of the fuel rail and the rail is essentially into the dead end (head)?

Or am I misreading? is the return line from the injectors now being sent straight to the tank?

Two Qs arise if not; are the injectors going to get hot as the relatively stagnant fuel absorbs heat? Can it also increase vapour lock?

The more we talk, the larger this can of enquisitive worms seems to be! 👀🤣

That's how i understood what he put as well so if it's not, we're both wrong!

Usually because of the position of the injectors and fuel rail, they get hot and vapour locks can occur - the fact the system is pressurised helps to avoid this but obviously as the fuel heats up, it builds pressure so the FPR releases that back to the tank. In turn this drops the pressure in the fuel rail allowing the fuel to boil easier and so it goes on.

I had a problem last year with my 760, where heat was making fuel vapourise in the return line so i bought some heat reflective sleeving :



As an experiment (becuase i was still getting vapourising problems) i added some simple cooking foil, shint side out round the fuel rails and feed line :



Crude, effective and oven-ready! The proper stuff is this, came from China but fairly quickly :

https://www.ebay.co.uk/itm/12mm-75mm...w/164120831962

Choose your size and length, wrap it round and secure with the Velcro. Thinking about it, the return line i actually used this, almost the same but you have to disconnect then slide the sleeve over and reconnect the fuel line :

https://www.ebay.co.uk/itm/Aluminise...m/193523949045

If you're getting heat-soak/fuel vapourisation problems in this weather then you need to find out why.