Cosworth Vega Starting Issues

[res0o7eb]

Problem 1: The external fuel pump is noisy and doesn't shut off with key turned to off position - had to disconnect the battery.
Any thoughts on what causes this? Did I burn up the pump when I ran it with no gas?
Seems to make the same noise when there was no gas and when there was gas. Could the in-tank pump not be working and causing no gas to the external pump? I don't know if fuel pressure got up to 39 PSI as I don't have a fuel pressure gauge, but I could hear some 'girgling' at the fuel pressure regulator while the external pump was still running just prior to when I disconnected the battery.
How to verify fuel pressure?
And I thought I smelled some gas fumes in the engine compartment. So, it seemed like it was getting some gas.

Problem 2: The sending unit/sensor that sticks out the side of the block between the #1 and #2 exhaust ports is broken and disconnected.
Could this cause a no start as well? I know there is a relationship between the oil pressure switch and engine start. This may just be a water temperature sending unit, though. Correct?

I have not verified spark or injector pulse, yet.

BACKGROUND:
I just began working on my factory stock Cosworth Vega #203 after sitting for the 6 years since I've owned it.
I bought it non-running and I can't remember what was wrong with it, but it sat in a field in southern Washington for years prior to my purchase.
Odometer shows 34K miles - don't know if it is accurate. But car is well-worn - paint faded, rust in battery tray/frame rail area.
The PAIR system was removed by a previous owner.
I have zero experience with the Cosworth Vega DOHC EFI engine. But, I know a little bit about the various components of the EFI system and how it all works in theory.

Anyway, thought I would try to get it running since I swapped out the ignition lock cylinder (lost original keys a LONG time ago. )
Need some help by the experts here.

Before attempting to start:
Oil looked good in both color and level - amazing!
Radiator was bone dry. Added water.
Pulled spark plugs - they looked OK. Re-installed. They are not AC plugs - some Japanese brand.
NOTE: Previous owner had put anti-size on the threads, so they loosened with no problem. Good? The plastic spark plug boots have white marks on them - 1 mark for cylinder #1, 2 marks for cylinder #2, etc. Is that from the factory?
Installed new battery. I could hear the noisy external fuel pump cycle on and off when I turned the key to on and then to off. Seemed like external fuel pump is working. All good.

I then attempted to start the motor. Engine cranks but no start after several attempts.
Oops, forgot to add gas. Not good. Added 4 gallons.
Attempted to start it again with gas in the tank this time. Cranks, but does not start. Not even close to firing. But, I thought I heard a faint hint of a cylinder or two trying to fire - perhaps wishful thinking.

[cosvega76]

Tom,

Problem 1: From my own experience, if the high pressure (HP) pump is noisy, the low pressure (LP) pump in the tank isn't supplying enough fuel. This could be a problem with the LP pump or a kink in the line or hose between the LP and HP pumps. The pumps should not run all the time, they are controlled by the computer. Either your pump relay is stuck closed, or someone bypassed the computer.

I would recommend getting a fuel pressure gauge so you can see what is going on. I made one out of some brass fittings and a 100-lb gauge from the plumbing department of the home-improvement store. It may not last long with the fuel, but you probably will only need it for this problem.

Problem 2: Which sending unit do you mean? There are two around the thermostat housing for coolant, one for the computer and one for the dash gauge. The one for the computer is important as it tells the computer the coolant temperature - but mainly if it is cold for enrichment. Then there is one down near the oil filter for the oil pressure light. In a Cosworth, the fuel pumps are controlled by the computer, not the oil pressure sensor.

You can check for spark like any HEI system. I have one of those testers that looks like a spark plug with an alligator clip on the side and no side electrode.

Someone marked those wires along the way, not done by the factory.

Since the fuel pump turned on then off when cycling the key, the computer is in control of the pumps. You may need to drop the fuel tank and see what surprises lurk in there. When I burned up my HP pump this year at Carlisle, I replaced the in-tank pump with one from a Fiero (and others) and bypassed the one under the seat. When I get time, I'll be writing up and article about the mods for the CVOA Magazine. You ARE a CVOA member, right?


Chuck

[hammerdown7]

Tom,

Good info from Chuck. My guess on the HP working regardless of key position is that the PO had problems popping the in-line fuse from the computer and decided to by pass it, wired the HP directly as a last resort to try and start the engine. It may be noisy because the rubber isolation pieces may be deteriorated, they do need to have fuel running through them to keep from overheating, depends on how long you cranked it. The Fiero V6 in-tank pump works well in replacing both stock pumps. You should also replace all the fuel hoses to be safe, some may not be EFI rated. The sensor between the header ports is for the water temp gauge.

Dick

[cosworth0135]

I too used a pump from a fiero, just need to extend the bracket that holds the intank pump 2" then bypass the external pump, call it done, worked great for me Timmy

[cozwurth]

Fiero pump.... Funny. I used a Fiero fuel pump in CV#1009 back in the early '90's and got slammed for "modifying" my car. Anyway, there is a fuel injection trouble shooting manual out there. I'm not sure if you can find an electronic version without being a CVOA member, but it will be very helpful in finding the trouble.